| Closed Access | Embargo | Metadata Only Access | Open Access | Restricted | Total | |
|---|---|---|---|---|---|---|
| Total | 1 | 5 | 1784 | 7120 | 6335 | |
| 9999 | - | - | - | 9 | 1 | 10 |
| 2024 | - | 3 | 9 | 205 | 40 | 257 |
| 2023 | - | 1 | 16 | 420 | 71 | 508 |
| 2022 | - | 1 | 42 | 448 | 106 | 597 |
| 2021 | - | - | 23 | 392 | 99 | 514 |
| 2020 | - | - | 27 | 357 | 102 | 486 |
| 2019 | - | - | 38 | 426 | 101 | 565 |
| 2018 | - | - | 28 | 369 | 81 | 478 |
| 2017 | - | - | 52 | 266 | 166 | 484 |
| 2016 | - | - | 49 | 302 | 210 | 561 |
| 2015 | - | - | 39 | 309 | 224 | 572 |
| 2014 | - | - | 38 | 154 | 398 | 590 |
| 2013 | - | - | 33 | 149 | 387 | 569 |
| 2012 | - | - | 55 | 92 | 308 | 455 |
| 2011 | - | - | 60 | 93 | 335 | 488 |
| 2010 | - | - | 56 | 113 | 309 | 478 |
| 2009 | - | - | 43 | 130 | 266 | 439 |
| 2008 | - | - | 56 | 148 | 266 | 470 |
| 2007 | - | - | 120 | 141 | 364 | 625 |
| 2006 | - | - | 74 | 141 | 277 | 492 |
| 2005 | - | - | 32 | 145 | 243 | 420 |
| 2004 | - | - | 33 | 203 | 216 | 452 |
| 2003 | - | - | 81 | 147 | 191 | 419 |
| 2002 | - | - | 72 | 122 | 125 | 319 |
| 2001 | - | - | 102 | 132 | 113 | 347 |
| 2000 | - | - | 76 | 140 | 94 | 310 |
| 1999 | 1 | - | 80 | 97 | 104 | 282 |
| 1998 | - | - | 98 | 108 | 104 | 310 |
| 1997 | - | - | 11 | 74 | 78 | 163 |
| 1996 | - | - | 19 | 55 | 95 | 169 |
| 1995 | - | - | 24 | 100 | 73 | 197 |
| 1994 | - | - | 15 | 100 | 71 | 186 |
| 1993 | - | - | 19 | 69 | 50 | 138 |
| 1992 | - | - | 22 | 82 | 65 | 169 |
| 1991 | - | - | 14 | 75 | 57 | 146 |
| 1990 | - | - | 9 | 61 | 54 | 124 |
| 1989 | - | - | 32 | 79 | 52 | 163 |
| 1988 | - | - | 20 | 94 | 51 | 165 |
| 1987 | - | - | 15 | 61 | 45 | 121 |
| 1986 | - | - | 11 | 94 | 45 | 150 |
| 1985 | - | - | 32 | 40 | 59 | 131 |
| 1984 | - | - | 14 | 41 | 54 | 109 |
| 1983 | - | - | 19 | 45 | 42 | 106 |
| 1982 | - | - | 16 | 41 | 10 | 67 |
| 1981 | - | - | 21 | 36 | 15 | 72 |
| 1980 | - | - | 6 | 25 | 31 | 62 |
| 1979 | - | - | 5 | 21 | 20 | 46 |
| 1978 | - | - | 4 | 20 | 18 | 42 |
| 1977 | - | - | 4 | 29 | 9 | 42 |
| 1976 | - | - | 1 | 23 | 5 | 29 |
| 1975 | - | - | 4 | 27 | 9 | 40 |
| 1974 | - | - | - | 23 | 6 | 29 |
| 1973 | - | - | 3 | 22 | 3 | 28 |
| 1972 | - | - | 4 | 8 | 1 | 13 |
| 1971 | - | - | 3 | 2 | 4 | 9 |
| 1970 | - | - | 1 | 4 | 3 | 8 |
| 1969 | - | - | - | 1 | 2 | 3 |
| 1968 | - | - | 1 | 2 | - | 3 |
| 1967 | - | - | - | 1 | - | 1 |
| 1965 | - | - | - | 1 | - | 1 |
| 0 | - | - | 3 | 6 | 7 | 16 |