Table 2. Metadata across all 2,751,420 open access publications on PubMed Central (PMCOA).
| Number (%) | ||
|---|---|---|
| Open access PMC articles | 2,751,420 | |
| Research | 2,285,193 (83%) | |
| Country | USA | 126,256 (26%) |
| China | 80,667 (17%) | |
| UK | 68,413 (14%) | |
| Other (n = 2,113) | 312,302 (65%) | |
| Field of science | Medicine | 1,175,753 (50%) |
| Health services | 299,299 (13%) | |
| Biology | 261,326 (11%) | |
| Other (n = 9) | 1,015,042 (37%) | |
| Characteristics | Median (IQR) | |
| Year of publication | 2015 (2012–2018) | |
| Authors per article | 5 (3–7) | |
| Figures per article | 3 (0–5) | |
| Tables per article | 1 (0–3) | |
| References per article | 32 (15–50) | |
| Citation count | 6 (2–15) | |
| Journal Impact Factor | 3.0 (2.4–4.4) |
Note that Country contains more than the total number of countries because many publications report locations other than country (e.g., state, city, etc.). Similarly, even though we have gone at great length to standardize names of journals (see Materials and methods), the reported number is likely an overestimate. Missing values: Research (240,244, 9%), Country (2,271,577, 83%), Field of science (396,331, 14%), Year (21,080, 1%), Citation count (870,186; 32%), and Journal Impact Factor (909,098; 33%). Note that the large number of missing data for Citation count and Field of science are due to many articles not having a PMID (some articles are on PMC but are not admitted to PubMed). Field of science was taken from SciTech, Citation count from OCC (April 17, 2020), and Journal Impact Factors of 2018 from WOS.
IQR, interquartile range; OCC, Open Citation Collection; PMC, PubMed Central; PMCOA, PubMed Central Open Access; PMID, PubMed ID; WOS, Web of Science.