| Year | Count |
|---|---|
| 1980 | 10 |
| 1981 | 16 |
| 1982 | 14 |
| 1983 | 8 |
| 1984 | 6 |
| 1985 | 20 |
| 1986 | 13 |
| 1987 | 5 |
| 1988 | 46 |
| 1989 | 61 |
| 1990 | 48 |
| 1991 | 77 |
| 1992 | 69 |
| 1993 | 63 |
| 1994 | 167 |
| 1995 | 194 |
| 1996 | 309 |
| 1997 | 337 |
| 1998 | 353 |
| 1999 | 318 |
| 2000 | 434 |
| 2001 | 422 |
| 2002 | 302 |
| 2003 | 291 |
| 2004 | 476 |
| 2005 | 441 |
| 2006 | 513 |
| 2007 | 555 |
| 2008 | 533 |
| 2009 | 612 |
| 2010 | 692 |
| 2011 | 935 |
| 2012 | 855 |
| 2013 | 799 |
| 2014 | 792 |
| 2015 | 774 |
| 2016 | 790 |
| 2017 | 683 |
| 2018 | 502 |
| 2019 | 556 |
| 2020 | 471 |
| 2021 | 486 |
| 2022 | 440 |
| 2023 | 377 |
| 2024 | 360 |