| Year | Count |
|---|---|
| 1971 | 7 |
| 1972 | 6 |
| 1974 | 8 |
| 1975 | 22 |
| 1976 | 22 |
| 1977 | 38 |
| 1978 | 54 |
| 1979 | 48 |
| 1980 | 61 |
| 1981 | 66 |
| 1982 | 99 |
| 1983 | 73 |
| 1984 | 108 |
| 1985 | 134 |
| 1986 | 170 |
| 1987 | 229 |
| 1988 | 235 |
| 1989 | 334 |
| 1990 | 5 |
| 1990 | 358 |
| 1991 | 431 |
| 1992 | 507 |
| 1993 | 601 |
| 1994 | 646 |
| 1995 | 465 |
| 1996 | 538 |
| 1997 | 457 |
| 1998 | 498 |
| 1999 | 542 |
| 2000 | 545 |
| 2001 | 480 |
| 2002 | 359 |
| 2003 | 405 |
| 2004 | 396 |
| 2005 | 424 |
| 2006 | 460 |
| 2007 | 359 |
| 2008 | 414 |
| 2009 | 304 |
| 2010 | 230 |
| 2011 | 199 |
| 2012 | 223 |
| 2013 | 176 |
| 2014 | 184 |
| 2015 | 168 |
| 2016 | 110 |
| 2017 | 188 |
| 2018 | 145 |
| 2019 | 78 |
| 2020 | 65 |
| 2021 | 133 |
| 2022 | 81 |
| 2023 | 71 |
| 2024 | 78 |