| Closed Access | Embargo | Metadata Only Access | Open Access | Restricted | Unknown | Total | |
|---|---|---|---|---|---|---|---|
| Total | 485 | 3 | 1854 | 2182 | 673 | 461 | |
| 2025 | - | - | - | 7 | 3 | - | 10 |
| 2024 | - | 1 | - | 88 | 14 | - | 103 |
| 2023 | 2 | - | 5 | 89 | 39 | - | 135 |
| 2022 | - | - | 13 | 174 | 61 | 6 | 254 |
| 2021 | 8 | 1 | 15 | 263 | 55 | 4 | 346 |
| 2020 | 11 | 1 | 12 | 186 | 59 | 5 | 274 |
| 2019 | 22 | - | 19 | 214 | 48 | 14 | 317 |
| 2018 | 3 | - | 32 | 91 | 39 | 5 | 170 |
| 2017 | 6 | - | 26 | 83 | 25 | 3 | 143 |
| 2016 | 16 | - | 25 | 145 | 10 | 15 | 211 |
| 2015 | 51 | - | 25 | 120 | 21 | 52 | 269 |
| 2014 | 62 | - | 159 | 155 | 19 | 42 | 437 |
| 2013 | 41 | - | 109 | 118 | 21 | 54 | 343 |
| 2012 | 35 | - | 106 | 126 | 16 | 44 | 327 |
| 2011 | 44 | - | 162 | 121 | 10 | 52 | 389 |
| 2010 | 10 | - | 227 | 56 | 14 | 27 | 334 |
| 2009 | 5 | - | 161 | 22 | 5 | 18 | 211 |
| 2008 | 9 | - | 180 | 14 | 11 | 18 | 232 |
| 2007 | 13 | - | 189 | 10 | 6 | 21 | 239 |
| 2006 | 13 | - | 153 | 7 | 6 | 25 | 204 |
| 2005 | 11 | - | 147 | 13 | 8 | 31 | 210 |
| 2004 | 12 | - | 9 | 17 | 15 | 6 | 59 |
| 2003 | 10 | - | 4 | 8 | 8 | 1 | 31 |
| 2002 | 15 | - | 9 | 9 | 7 | 2 | 42 |
| 2001 | 10 | - | 8 | 12 | 14 | 3 | 47 |
| 2000 | 12 | - | 7 | 9 | 13 | 2 | 43 |
| 1999 | 4 | - | 7 | 3 | 15 | 1 | 30 |
| 1998 | 7 | - | 14 | 1 | 22 | 2 | 46 |
| 1997 | 5 | - | 1 | 4 | 16 | 4 | 30 |
| 1996 | 10 | - | 6 | 2 | 14 | 2 | 34 |
| 1995 | 8 | - | 5 | 4 | 9 | - | 26 |
| 1994 | 8 | - | 3 | 3 | 6 | - | 20 |
| 1993 | 6 | - | 3 | 4 | 9 | 2 | 24 |
| 1992 | 4 | - | 1 | 1 | 8 | - | 14 |
| 1991 | 2 | - | 6 | 2 | 11 | - | 21 |
| 1990 | 4 | - | 3 | 1 | 5 | - | 13 |
| 1989 | 3 | - | 1 | - | 4 | - | 8 |
| 1988 | 2 | - | - | - | 4 | - | 6 |
| 1987 | - | - | 2 | - | - | - | 2 |
| 1986 | - | - | - | - | 2 | - | 2 |
| 1985 | - | - | - | - | 1 | - | 1 |
| 1984 | 1 | - | - | - | - | - | 1 |