Open access grew from 22% of the article records tracked in 2015 to 59% in 2022 and 2023. The latest year in the global series, 2024, recorded 2,911,329 open-access articles, representing 47% of the dataset’s articles. These figures show both the long-term expansion of freely available research and a recent change in the measured share.
Contents
- Global open-access output
- The growth of Gold open access
- Green, Hybrid, Bronze, and Diamond routes
- How routes changed over time
- Open access by academic discipline
- Countries and income groups
- Citation impact patterns
Global open-access output
The global series in Open Access Trends in Scholarly Publishing 2015–2024 reports a sustained rise in both the number and share of open-access articles from 2015 through 2023. In 2015, 1,605,639 article records were open access, equal to 22% of all articles in the dataset. The count rose to 1,796,599 in 2016, or 25%, and to 2,033,687 in 2017, or 30%.
The expansion continued in 2018, when 2,294,978 records were open access, representing 34%. In 2019, the count reached 2,573,663, or 37%. The 2020 total was 2,965,644, equal to 42%, followed by 3,225,595 in 2021, equal to 49%.
The series reached 3,393,457 open-access records in 2022, when the share was 59%. It remained at 59% in 2023, with 3,561,878 open-access records. In 2024, the reported count was 2,911,329 and the share was 47%. The 2024 figure should be read as the latest observation in this series, not as evidence that the longer-term expansion was reversed: the source reports the measurement but does not establish why the count or share differs from 2023.
| Year | Open-access articles | Share of all articles |
|---|---|---|
| 2015 | 1,605,639 | 22% |
| 2018 | 2,294,978 | 34% |
| 2020 | 2,965,644 | 42% |
| 2022 | 3,393,457 | 59% |
| 2023 | 3,561,878 | 59% |
| 2024 | 2,911,329 | 47% |
Source: Open Access Trends in Scholarly Publishing 2015–2024. The source’s article-record counts and percentages describe the dataset used for that report; they are not a universal census of every scholarly publication.
The growth of Gold open access
Gold open access—articles published in journals that provide open access at publication—accounted for a growing part of the measured literature. Gold articles numbered 469,785 in 2015, or 7% of all articles in the dataset. The count rose to 557,612 in 2016, or 8%, and 702,565 in 2017, or 10%.
In 2018, Gold open-access articles reached 875,884, equal to 13% of all articles. The figure increased to 1,135,782 in 2019, or 16%, and 1,336,558 in 2020, or 19%. Gold output reached 1,434,708 in 2021, equal to 22%, and 1,452,620 in 2022, equal to 25%.
The Gold count was 1,432,676 in 2023, or 24% of all articles, and 1,308,519 in 2024, or 21%. Within the reported series, Gold therefore became the largest measured open-access route by share, although the count and percentage were lower in 2024 than in the two preceding years.
Green, Hybrid, Bronze, and Diamond routes
Green open access, which covers articles made available through repositories or related archiving routes, was smaller than Gold throughout the reported period. Green articles numbered 281,820 in 2015, or 4% of all articles, and 310,242 in 2016, also 4%. The count reached 319,494 in 2017 and 327,405 in 2018, with each year representing 5%.
Green output was 326,319 in 2019, or 5%, and 363,347 in 2020, also 5%. It rose to 377,780 in 2021, or 6%, and 388,292 in 2022, or 7%. The reported count then fell to 297,866 in 2023, or 5%, and 134,560 in 2024, or 2%. These are source-reported observations; the figures alone do not identify the causes of the later decline.
The open-access total also includes Hybrid, Bronze, and Diamond categories. Hybrid refers to open articles in otherwise subscription-based journals, while Bronze describes openly readable articles without the same route classification; Diamond is a distinct open-access route in the source’s classification. The route shares below are percentages among that year’s open-access articles, not percentages of all articles.
How routes changed over time
Gold’s share of open-access articles increased from 29% in 2015 to 45% in 2024, after reaching 44% in 2019, 45% in 2020, 44% in 2021, 43% in 2022, and 40% in 2023. Over the same comparison, Green fell from 18% in 2015 to 5% in 2024. Hybrid moved from 12% to 24%, while Bronze moved from 29% to 13%. Diamond was 12% in 2015 and 13% in 2024.
| Year | Gold | Hybrid | Bronze | Green | Diamond |
|---|---|---|---|---|---|
| 2015 | 29% | 12% | 29% | 18% | 12% |
| 2020 | 45% | 12% | 19% | 12% | 12% |
| 2022 | 43% | 18% | 17% | 11% | 11% |
| 2024 | 45% | 24% | 13% | 5% | 13% |
The annual route distribution shows that the growth in open access was not evenly distributed among routes. In 2016, Gold represented 31% of open-access articles, Hybrid 12%, Bronze 27%, Green 17%, and Diamond 13%. In 2017 the corresponding shares were 35%, 11%, 25%, 16%, and 13%; in 2018 they were 38%, 11%, 23%, 14%, and 13%.
For 2019 through 2021, Gold represented 44%, 45%, and 44%, respectively. Hybrid represented 10%, 12%, and 14%; Bronze represented 21%, 19%, and 18%; Green represented 13%, 12%, and 12%; and Diamond represented 12% in each year. In 2022, the shares were 43% Gold, 18% Hybrid, 17% Bronze, 11% Green, and 11% Diamond. In 2023, they were 40%, 22%, 18%, 8%, and 11%.
All route figures in this section come from Open Access Trends in Scholarly Publishing 2015–2024. Category definitions and the source’s coverage determine how an article is assigned to a route.
Open access by academic discipline
The 2024 discipline snapshot reports different open-access shares across four academic domains. Physical Sciences had 2,568,474 publications, of which 967,336 were open access, or 38%. Social Sciences had 2,053,499 publications, including 839,687 open-access publications, or 41%.
Health Sciences had 1,594,127 publications and 782,726 open-access publications, giving an open-access share of 49%. Life Sciences had 815,338 publications, of which 427,869 were open access, or 52%.
| 2024 domain | Publications | Open-access publications | Open-access share |
|---|---|---|---|
| Physical Sciences | 2,568,474 | 967,336 | 38% |
| Social Sciences | 2,053,499 | 839,687 | 41% |
| Health Sciences | 1,594,127 | 782,726 | 49% |
| Life Sciences | 815,338 | 427,869 | 52% |
The discipline figures come from Snapshot 2024: Open Access by Academic Discipline. They describe the four domains and measurement period covered by that snapshot; they should not be generalized to every field or publication type.
Countries and income groups
The global pattern also changed across countries and economies. In 2012, 99%—157 of 159—had more closed-access than Gold open-access articles among units with more than 10 fractionally counted publications. By 2017, the comparable figure was 85%, or 142 of 167. In 2022, it was 46%, or 83 of 182.
The reverse comparison shows the same shift. In 2012, only two countries, the Gambia and Guinea-Bissau, had a Gold open-access-to-closed-access ratio above 1:1. In 2017, 25 countries or economies, representing 15%, were above that ratio. In 2022, 54%, or 99 countries or economies, were above it.
Income-group shares do not follow the same pattern as absolute output. In 2022, Gold open access represented 30% of articles by high-income-country authors, matching the upper-middle-income share. It represented 62% of articles by low-income-country authors. However, high-income countries or economies contributed 460,979 fractionally counted Gold open-access articles, or 48% of the total, while upper-middle-income countries contributed 381,556, or 40%. Low-income countries contributed 8,132, or less than 1%.
For country-specific trends, the Gold open-access share among China-affiliated articles increased from 6% to 28% between 2012 and 2022. Among India-affiliated articles, it increased from 10% to 17% over the same period. These are changes in shares across the stated years, not forecasts.
These country, income-group, and time-series measures are from NSF 25-347 Open-Access Publishing in a Global Context. The source uses fractionally counted publications for the output totals and defines an analytic population for the country comparisons.
Citation impact patterns
The NSF report also gives HCA ratios for articles in the global top 1% by citations. In 2020, the HCA ratio for Gold open-access articles was 0.74, meaning 0.74% were in the global top 1% by citations. The ratio for Green open-access articles was 2.01, meaning 2.01% were in that top-citation group.
For longer historical comparisons, the HCA ratio for closed-access articles changed from 1.10 to 0.83 between 2003 and 2020. The ratio for Other Journal-Based OA articles changed from 1.49 to 2.00 across the same period. These reported ratios compare citation concentration with the global top-1% benchmark; they do not establish that access status caused a particular citation outcome.
The measurement periods matter when interpreting these results. The 2020 HCA values are a single-year observation, while the 2003–2020 values describe changes across a longer span. Together with the country and discipline measures, they show why open-access publishing statistics need route definitions, geography, income classification, and citation methodology alongside headline percentages.
Source: NSF 25-347 Open-Access Publishing in a Global Context.