| Closed Access | Embargo | Metadata Only Access | Open Access | Restricted | Unknown | Total | |
|---|---|---|---|---|---|---|---|
| Total | 449 | 3 | 1777 | 2222 | 788 | 452 | |
| 2025 | - | - | - | 7 | 3 | - | 10 |
| 2024 | - | 1 | - | 89 | 13 | - | 103 |
| 2023 | 2 | - | 5 | 90 | 39 | - | 136 |
| 2022 | - | - | 13 | 175 | 58 | 8 | 254 |
| 2021 | 7 | 1 | 15 | 264 | 56 | 4 | 347 |
| 2020 | 12 | 1 | 12 | 185 | 58 | 5 | 273 |
| 2019 | 23 | - | 20 | 216 | 48 | 14 | 321 |
| 2018 | 3 | - | 31 | 91 | 42 | 6 | 173 |
| 2017 | 6 | - | 24 | 88 | 28 | 4 | 150 |
| 2016 | 16 | - | 25 | 145 | 10 | 15 | 211 |
| 2015 | 50 | - | 24 | 124 | 20 | 51 | 269 |
| 2014 | 61 | - | 156 | 154 | 21 | 44 | 436 |
| 2013 | 41 | - | 107 | 119 | 21 | 55 | 343 |
| 2012 | 35 | - | 101 | 127 | 18 | 45 | 326 |
| 2011 | 41 | - | 162 | 121 | 13 | 52 | 389 |
| 2010 | 9 | - | 222 | 56 | 19 | 28 | 334 |
| 2009 | 4 | - | 158 | 22 | 6 | 21 | 211 |
| 2008 | 8 | - | 171 | 16 | 21 | 17 | 233 |
| 2007 | 5 | - | 177 | 18 | 32 | 14 | 246 |
| 2006 | 4 | - | 134 | 16 | 31 | 28 | 213 |
| 2005 | 6 | - | 135 | 19 | 38 | 21 | 219 |
| 2004 | 12 | - | 8 | 17 | 24 | 3 | 64 |
| 2003 | 9 | - | 4 | 8 | 9 | 1 | 31 |
| 2002 | 13 | - | 9 | 10 | 10 | 1 | 43 |
| 2001 | 9 | - | 7 | 12 | 16 | 3 | 47 |
| 2000 | 11 | - | 7 | 9 | 15 | 1 | 43 |
| 1999 | 4 | - | 7 | 3 | 15 | 1 | 30 |
| 1998 | 7 | - | 14 | 1 | 21 | 2 | 45 |
| 1997 | 5 | - | 1 | 4 | 13 | 4 | 27 |
| 1996 | 10 | - | 6 | 2 | 14 | 2 | 34 |
| 1995 | 7 | - | 4 | 4 | 8 | - | 23 |
| 1994 | 8 | - | 3 | 3 | 5 | - | 19 |
| 1993 | 6 | - | 3 | 4 | 8 | 2 | 23 |
| 1992 | 4 | - | 1 | 1 | 8 | - | 14 |
| 1991 | 2 | - | 5 | 1 | 11 | - | 19 |
| 1990 | 4 | - | 3 | 1 | 5 | - | 13 |
| 1989 | 3 | - | 1 | - | 4 | - | 8 |
| 1988 | 1 | - | - | - | 4 | - | 5 |
| 1987 | - | - | 2 | - | - | - | 2 |
| 1986 | - | - | - | - | 2 | - | 2 |
| 1985 | - | - | - | - | 1 | - | 1 |
| 1984 | 1 | - | - | - | - | - | 1 |