# Social and Human Service Assistants

US SOC code 21-1093. Markdown version of https://futurehistory.earth/timeline/21-1093

Also called: Human service assistant, Case aide, Case worker assistant, Social service aide, Social services assistant.

## In brief

In May 2025, [BLS](https://www.bls.gov/oes/special-requests/oesm25nat.zip) counted **437,860** US social and human service assistants, with median pay of **$45,930** a year. The earliest figure here is [an estimate](https://en.wikipedia.org/wiki/Social_Security_Act) of **40,000** from 1935, not measured the same way as today's count. The last full technology era for social and human service assistants: Electronic case management systems, 2000 to 2010.

## What the sources say

### Official outlook

BLS projects employment to grow 7.4% from 2025 to 2035. Source: [BLS Employment Projections 2025-35](https://data.bls.gov/projections/nationalMatrix?queryParams=21-1093&ioType=o).

### AI exposure studies

- **37.5%** of this job's tasks are exposed to large language models. Not a forecast of job losses. [Eloundou and others, 2023](https://github.com/openai/GPTs-are-GPTs/blob/main/data/occ_level.csv)
- **0.13** estimated probability that the whole occupation could be computerised, over an unspecified number of years. Not a forecast of job losses. [Frey and Osborne, 2013](https://oms-www.files.svdcdn.com/production/downloads/academic/The_Future_of_Employment.pdf)

Data as of BLS OEWS May 2025; BLS Employment Projections 2025-35.

## Social and Human Service Assistants employment and pay by year

- On record since: 1889
- Latest US employment: 437,860 (May 2025). Source: BLS OEWS May 2025 [5]
- Latest US median pay: $45,930 (May 2025). Source: BLS OEWS May 2025 [14]
- Outlook: +7.4% by 2035. Source: BLS Employment Projections 2025-35 [31]

### In other countries

The latest figure each country's statistics agency publishes for this job. Each uses its own occupation definition, survey basis and currency, so the numbers are not directly comparable with each other or with the US figures.

- **United Kingdom** (UK SOC 3229)
  - Employment, 2025: 146,000. Source: ONS ASHE 2025 [11]. ONS Annual Survey of Hours and Earnings (Table 14): employee jobs in SOC 3229 Welfare and housing associate professionals n.e.c., United Kingdom, 2025 (ASHE "number of jobs", thousands x1000; excludes self-employment). Open Government Licence v3.0.
  - Median pay, 2025: £26,640. Source: ONS ASHE 2025 [19]. ONS Annual Survey of Hours and Earnings (Table 14.7a): median gross annual pay for all employee jobs in SOC 3229 Welfare and housing associate professionals n.e.c., United Kingdom, 2025. Open Government Licence v3.0.
- **Australia** (ANZSCO 4117)
  - Employment, 2025: 90,600. Source: ABS Labour Force Survey [12]. ABS Labour Force Survey (Detailed), table EQ08: employed persons in ANZSCO 4117 Welfare Support Workers, national (summed across sex and state/territory), annual average of 4 quarterly estimates.
  - Median pay, 2025: A$95,888. Source: ABS Employee Earnings May 2025 [20]. Annualised (x52) from A$1,844 median weekly earnings. ABS Survey of Employee Earnings and Hours, May 2025: median pay for full-time non-managerial employees paid at the adult rate, before tax. Surfaced via the Jobs and Skills Australia occupation profile.

### All 27 years of cited US data

| Year | US employment | Annual pay (median unless marked) | Source |
| --- | --- | --- | --- |
| 1935 | 40,000 (estimate) | n/a | Est., Wikipedia [1] |
| 1965 | 95,000 (estimate) | n/a | Est., Wikipedia [2] |
| 1996 | 270,000 (estimate) | n/a | Est., Wikipedia [3] |
| 2000 | 260,910 | $24,000 (estimate) | BLS OEWS 2000 (employment) [4]; Est., BLS Occupational Outlook Handbook (pay) [13] |
| 2003 | 300,310 | $23,860 | BLS OEWS May 2003 [5] |
| 2004 | 331,860 | $24,270 | BLS OEWS May 2004 [5] |
| 2005 | 313,210 | $25,030 | BLS OEWS May 2005 [5] |
| 2006 | 318,620 | $25,580 | BLS OEWS May 2006 [5] |
| 2007 | 316,380 | $26,630 | BLS OEWS May 2007 [5] |
| 2008 | 332,880 | $27,280 | BLS OEWS May 2008 [5] |
| 2009 | 344,050 | $27,940 | BLS OEWS May 2009 [5] |
| 2010 | 357,500 | $28,200 | BLS OEWS May 2010 (employment) [5]; BLS OEWS 2010 (pay) [13] |
| 2011 | 359,860 | $28,740 | BLS OEWS May 2011 [5] |
| 2012 | 351,400 | $28,850 | BLS OEWS May 2012 [5] |
| 2013 | 355,500 | $29,230 | BLS OEWS May 2013 [5] |
| 2014 | 354,800 | $29,790 | BLS OEWS 2014 (employment) [6]; BLS OEWS May 2014 (pay) [14] |
| 2015 | 359,350 | $30,830 | BLS OEWS May 2015 [5] |
| 2016 | 360,650 | $31,810 | BLS OEWS May 2016 [5] |
| 2017 | 384,080 | $33,120 | BLS OEWS May 2017 [5] |
| 2018 | 392,300 | $33,750 | BLS OEWS May 2018 [5] |
| 2019 | 404,450 | $35,060 | BLS OEWS May 2019 [5] |
| 2020 | 399,920 | $35,960 | BLS OEWS May 2020 [5] |
| 2021 | 398,380 | $37,610 | BLS OEWS May 2021 (employment) [7]; BLS OEWS 2021 (pay) [13] |
| 2022 | 399,560 | $38,520 | BLS OEWS May 2022 [5] |
| 2023 | 409,310 | $41,410 | BLS OEWS May 2023 [5] |
| 2024 | 424,220 | $45,120 | BLS OEWS May 2024 [5] |
| 2025 | 437,860 | $45,930 | BLS OEWS May 2025 [5] |

## Sources (101)

### Employment series

1. [Wikipedia — Social Security Act (1935 founding, eligibility worker infrastructure created)](https://en.wikipedia.org/wiki/Social_Security_Act), Wikipedia
2. [Wikipedia — Great Society (Medicaid July 30, 1965; Economic Opportunity Act 1964; community action programs)](https://en.wikipedia.org/wiki/Great_Society), Wikipedia
3. [Wikipedia — Personal Responsibility and Work Opportunity Act (PRWORA 1996; 60% caseload decline 1994-2005; TANF work-requirement caseload complexity)](https://en.wikipedia.org/wiki/Personal_Responsibility_and_Work_Opportunity_Act), Wikipedia
4. [BLS OES 2000 national estimates (flat file)](https://www.bls.gov/oes/special-requests/oes00nat.zip), Bureau of Labor Statistics
5. BLS OEWS, national cross-industry estimates (flat file), Bureau of Labor Statistics. Editions: [2003](https://www.bls.gov/oes/special-requests/oesm03nat.zip), [2004](https://www.bls.gov/oes/special-requests/oesm04nat.zip), [2005](https://www.bls.gov/oes/special-requests/oesm05nat.zip), [2006](https://www.bls.gov/oes/special-requests/oesm06nat.zip), [2007](https://www.bls.gov/oes/special-requests/oesm07nat.zip), [2008](https://www.bls.gov/oes/special-requests/oesm08nat.zip), [2009](https://www.bls.gov/oes/special-requests/oesm09nat.zip), [2010](https://www.bls.gov/oes/special-requests/oesm10nat.zip), [2011](https://www.bls.gov/oes/special-requests/oesm11nat.zip), [2012](https://www.bls.gov/oes/special-requests/oesm12nat.zip), [2013](https://www.bls.gov/oes/special-requests/oesm13nat.zip), [2015](https://www.bls.gov/oes/special-requests/oesm15nat.zip), [2016](https://www.bls.gov/oes/special-requests/oesm16nat.zip), [2017](https://www.bls.gov/oes/special-requests/oesm17nat.zip), [2018](https://www.bls.gov/oes/special-requests/oesm18nat.zip), [2019](https://www.bls.gov/oes/special-requests/oesm19nat.zip), [2020](https://www.bls.gov/oes/special-requests/oesm20nat.zip), [2022](https://www.bls.gov/oes/special-requests/oesm22nat.zip), [2023](https://www.bls.gov/oes/special-requests/oesm23nat.zip), [2024](https://www.bls.gov/oes/special-requests/oesm24nat.zip), [2025](https://www.bls.gov/oes/special-requests/oesm25nat.zip)
6. [BLS Occupational Outlook Handbook — Social and Human Service Assistants (2014 employment, ACA Medicaid expansion context)](https://www.bls.gov/ooh/community-and-social-service/social-and-human-service-assistants.htm), Bureau of Labor Statistics
7. [BLS OEWS May 2021 — Social and Human Service Assistants (21-1093), national employment](https://www.bls.gov/oes/2021/may/oes211093.htm), U.S. Bureau of Labor Statistics
8. ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 3232, United Kingdom. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0., Office for National Statistics. Editions: [2002](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2002/2002-table-14.zip), [2006](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2006consistentw_007methodology/2006-table-14.zip), [2010](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2010revised/2010-revised-table-14.zip)
9. ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 3239, United Kingdom. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0., Office for National Statistics. Editions: [2011](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2011revisedbasedonsoc2010/2011-revised-table-14.zip), [2015](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2015/table142015revised.zip), [2020](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2020revised/table142020revised.zip)
10. [ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 3229, United Kingdom, 2022. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0.](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2022revised/ashetable142022revised.zip), Office for National Statistics
11. [ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 3229, United Kingdom, 2025. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0.](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2025provisional/ashetable142025provisional.zip), Office for National Statistics
12. [ABS: Labour Force, Australia, Detailed, table EQ08 (Employed persons by Occupation unit group, ANZSCO 2013), latest release](https://www.abs.gov.au/statistics/labour/employment-and-unemployment/labour-force-australia-detailed/latest-release), Australian Bureau of Statistics

### Wage series

13. [BLS Occupational Outlook Handbook — Social and Human Service Assistants (historical wage context; ~$24k nominal estimate circa 2000)](https://www.bls.gov/ooh/community-and-social-service/social-and-human-service-assistants.htm), Bureau of Labor Statistics
14. BLS OEWS, national cross-industry estimates (flat file), Bureau of Labor Statistics. Editions: [2003](https://www.bls.gov/oes/special-requests/oesm03nat.zip), [2004](https://www.bls.gov/oes/special-requests/oesm04nat.zip), [2005](https://www.bls.gov/oes/special-requests/oesm05nat.zip), [2006](https://www.bls.gov/oes/special-requests/oesm06nat.zip), [2007](https://www.bls.gov/oes/special-requests/oesm07nat.zip), [2008](https://www.bls.gov/oes/special-requests/oesm08nat.zip), [2009](https://www.bls.gov/oes/special-requests/oesm09nat.zip), [2011](https://www.bls.gov/oes/special-requests/oesm11nat.zip), [2012](https://www.bls.gov/oes/special-requests/oesm12nat.zip), [2013](https://www.bls.gov/oes/special-requests/oesm13nat.zip), [2014](https://www.bls.gov/oes/special-requests/oesm14nat.zip), [2015](https://www.bls.gov/oes/special-requests/oesm15nat.zip), [2016](https://www.bls.gov/oes/special-requests/oesm16nat.zip), [2017](https://www.bls.gov/oes/special-requests/oesm17nat.zip), [2018](https://www.bls.gov/oes/special-requests/oesm18nat.zip), [2019](https://www.bls.gov/oes/special-requests/oesm19nat.zip), [2020](https://www.bls.gov/oes/special-requests/oesm20nat.zip), [2022](https://www.bls.gov/oes/special-requests/oesm22nat.zip), [2023](https://www.bls.gov/oes/special-requests/oesm23nat.zip), [2025](https://www.bls.gov/oes/special-requests/oesm25nat.zip)
15. [BLS OEWS May 2024, national cross-industry estimates (flat file)](https://www.bls.gov/oes/special-requests/oesm24nat.zip), U.S. Bureau of Labor Statistics
16. ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 3232, United Kingdom. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0., Office for National Statistics. Editions: [2002](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2002/2002-table-14.zip), [2006](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2006consistentw_007methodology/2006-table-14.zip), [2010](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2010revised/2010-revised-table-14.zip)
17. ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 3239, United Kingdom. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0., Office for National Statistics. Editions: [2011](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2011revisedbasedonsoc2010/2011-revised-table-14.zip), [2015](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2015/table142015revised.zip), [2020](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2020revised/table142020revised.zip)
18. [ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 3229, United Kingdom, 2022. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0.](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2022revised/ashetable142022revised.zip), Office for National Statistics
19. [ONS: Annual Survey of Hours and Earnings, Table 14.7a (Annual pay - Gross), 4-digit SOC 3229, United Kingdom, 2025. Office for National Statistics, Annual Survey of Hours and Earnings, Table 14. Licensed under the Open Government Licence v3.0.](https://www.ons.gov.uk/file?uri=/employmentandlabourmarket/peopleinwork/earningsandworkinghours/datasets/occupation4digitsoc2010ashetable14/2025provisional/ashetable142025provisional.zip), Office for National Statistics
20. [Jobs and Skills Australia: Welfare Support Workers (ABS Survey of Employee Earnings and Hours, May 2025)](https://www.jobsandskills.gov.au/data/occupation-and-industry-profiles/occupations/4117-welfare-support-workers), Jobs and Skills Australia / Australian Bureau of Statistics

### Tool eras

21. [Wikipedia — Jane Addams (Hull House 1889; settlement house services; 2,000 weekly visitors at peak)](https://en.wikipedia.org/wiki/Jane_Addams), Wikipedia
22. [Wikipedia — Social work (COS origins; New York Charity Organization Society philanthropy courses 1898; Columbia SSW founding)](https://en.wikipedia.org/wiki/Social_work), Wikipedia
23. [Wikipedia — Social Security Act (1935; established Social Security Board; eligibility determination infrastructure)](https://en.wikipedia.org/wiki/Social_Security_Act), Wikipedia
24. [Wikipedia — Great Society (Medicare/Medicaid July 30, 1965; $1B Economic Opportunity Act; 100 community health centers by 1971)](https://en.wikipedia.org/wiki/Great_Society), Wikipedia
25. [Wikipedia — Supplemental Nutrition Assistance Program (Food Stamps to 15 million participants by October 1974)](https://en.wikipedia.org/wiki/Supplemental_Nutrition_Assistance_Program), Wikipedia
26. [Wikipedia — Personal Responsibility and Work Opportunity Act (PRWORA 1996; 53% caseload decline 1997-2000; TANF work-program complexity)](https://en.wikipedia.org/wiki/Personal_Responsibility_and_Work_Opportunity_Act), Wikipedia
27. [Wikipedia — Medicaid (enrollment from 39.9M in 2002 to 62.9M in 2009)](https://en.wikipedia.org/wiki/Medicaid), Wikipedia
28. [Wikipedia — Affordable Care Act (March 23, 2010 passage; Medicaid expansion to 138% FPL; 32 states + DC by December 2016)](https://en.wikipedia.org/wiki/Affordable_Care_Act), Wikipedia
29. [Wikipedia — American Rescue Plan Act of 2021 (CTC $3,000-$3,600/child; 2+ million children above poverty line)](https://en.wikipedia.org/wiki/American_Rescue_Plan_Act_of_2021), Wikipedia
30. [O\*NET 21-1093.00 — BLS 2024-34 projections (+6.4%, 28,900 new positions, 50,600 annual openings)](https://www.onetonline.org/link/summary/21-1093.00), O\*NET / BLS

### Forecasts and exposure studies

31. [BLS Employment Projections 2025-35, National Employment Matrix: 21-1093 Social and human service assistants (2025: 463.4 thousand; 2035: 497.6 thousand; +7.4%)](https://data.bls.gov/projections/nationalMatrix?queryParams=21-1093&ioType=o), Bureau of Labor Statistics
32. [Frey & Osborne (2013), "The Future of Employment: How Susceptible Are Jobs to Computerisation?", Appendix (SOC 21-1093 Social and Human Service Assistants: probability 0.13, rank 185 of 702)](https://oms-www.files.svdcdn.com/production/downloads/academic/The_Future_of_Employment.pdf), Oxford Martin School, University of Oxford
33. [Eloundou, Manning, Mishkin & Rock (2023), "GPTs are GPTs", occupation-level exposure data occ\_level.csv (O\*NET-SOC 21-1093.00, human-rated β 0.375)](https://github.com/openai/GPTs-are-GPTs/blob/main/data/occ_level.csv), OpenAI

### Historical notes

34. [Wikipedia — Jane Addams (Hull House 1889; 2,000 weekly visitors; 13-building complex; 500 settlement houses by 1920)](https://en.wikipedia.org/wiki/Jane_Addams), Wikipedia
35. [Wikipedia — Social work (New York COS philanthropy courses 1898; Columbia SSW founding)](https://en.wikipedia.org/wiki/Social_work), Wikipedia
36. [Wikipedia — Social Security Act (August 14, 1935; Aid to Dependent Children; eligibility determination at county level)](https://en.wikipedia.org/wiki/Social_Security_Act), Wikipedia
37. [Wikipedia — Great Society (Medicare/Medicaid July 30, 1965; Medicaid Title XIX; community action programs)](https://en.wikipedia.org/wiki/Great_Society), Wikipedia
38. [Wikipedia — Personal Responsibility and Work Opportunity Act (signed August 22, 1996; 53% caseload decline 1997-2000; three HHS resignations)](https://en.wikipedia.org/wiki/Personal_Responsibility_and_Work_Opportunity_Act), Wikipedia
39. [Wikipedia — Affordable Care Act (signed March 23, 2010; Medicaid expansion; 32 states + DC by 2016; 11M newly enrolled per CBO)](https://en.wikipedia.org/wiki/Affordable_Care_Act), Wikipedia
40. [Wikipedia — American Rescue Plan Act of 2021 (CTC $3,000-$3,600/child; fully refundable; 2+ million children above poverty line)](https://en.wikipedia.org/wiki/American_Rescue_Plan_Act_of_2021), Wikipedia
41. [Wikipedia — Medicaid (92 million enrolled by 2022; continuous enrollment unwinding 2023)](https://en.wikipedia.org/wiki/Medicaid), Wikipedia

### Predecessors & successors

42. [Wikipedia — Jane Addams (Hull House settlement workers; 2,000 weekly visitors at peak)](https://en.wikipedia.org/wiki/Jane_Addams), Wikipedia
43. [Wikipedia — Social Security Act (1935; eligibility determination infrastructure)](https://en.wikipedia.org/wiki/Social_Security_Act), Wikipedia
44. [Wikipedia — Great Society (Economic Opportunity Act 1964; community action programs)](https://en.wikipedia.org/wiki/Great_Society), Wikipedia

### Present-day analysis

- [BLS Occupational Outlook Handbook — Social and Human Service Assistants (2024-34 projections)](https://www.bls.gov/ooh/community-and-social-service/social-and-human-service-assistants.htm), accessed 2026-06-03
- [O\*NET 30.3 — Social and Human Service Assistants (21-1093.00)](https://www.onetonline.org/link/summary/21-1093.00), accessed 2026-06-03
- [Eloundou et al. 2024 — GPTs are GPTs (Science)](https://arxiv.org/abs/2303.10130), accessed 2026-06-03
- [APHSA — Person-Centered AI in Human Services: Letting Technology Assist, Not Decide (2025)](https://aphsa.org/resources/person-centered-ai-in-human-services-letting-technology-assist-not-decide/), accessed 2026-06-03
- [Netsmart — 5 Ways Automation Is Transforming Human Services Workflows (Bells AI: 67% documentation time savings)](https://www.ntst.com/blog/2025/5-ways-automation-is-transforming-human-services-workflows), accessed 2026-06-03
- [CaseWorthy — Cara AI for Human Services (case summaries, face sheets, natural language queries)](https://caseworthy.com/platform/artificial-intelligence-for-human-services/), accessed 2026-06-03
- [Northwoods — Traverse Case Discovery 2.0, Family Mapping, Ada modules (2025)](https://www.teamnorthwoods.com/resources/blog/introducing-our-newest-traverse-modules-smarter-faster-case-understanding/), accessed 2026-06-03
- [Unite Us — Closed-Loop Referral System (SDOH screening and community resource navigation)](https://uniteus.com/products/closed-loop-referral-system/), accessed 2026-06-03
- [Northwoods — AI and ChatGPT for Human Services and Social Work: Dos and Donts](https://www.teamnorthwoods.com/resources/blog/artificial-intelligence-and-chatgpt-for-human-services-and-social-work-dos-and-donts/), accessed 2026-06-03
- [CaseWorthy — Revolutionizing Case Management with AI (AI-driven client journey analysis)](https://caseworthy.com/articles/revolutionizing-case-management-with-ai/), accessed 2026-06-03

How to read these figures: https://futurehistory.earth/methodology. Every figure links to its own source; gaps stay gaps.