| Year | Count |
|---|---|
| 1968 | 5 |
| 1976 | 5 |
| 1977 | 10 |
| 1978 | 18 |
| 1979 | 5 |
| 1980 | 21 |
| 1981 | 20 |
| 1982 | 6 |
| 1984 | 28 |
| 1985 | 24 |
| 1986 | 37 |
| 1987 | 27 |
| 1988 | 11 |
| 1989 | 40 |
| 1990 | 40 |
| 1991 | 65 |
| 1992 | 50 |
| 1993 | 64 |
| 1994 | 77 |
| 1995 | 155 |
| 1996 | 277 |
| 1997 | 478 |
| 1998 | 496 |
| 1999 | 514 |
| 2000 | 562 |
| 2001 | 797 |
| 2002 | 821 |
| 2003 | 1,091 |
| 2004 | 1,122 |
| 2005 | 1,160 |
| 2006 | 1,069 |
| 2007 | 967 |
| 2008 | 859 |
| 2009 | 770 |
| 2010 | 637 |
| 2011 | 577 |
| 2012 | 554 |
| 2013 | 541 |
| 2014 | 527 |
| 2015 | 591 |
| 2016 | 505 |
| 2017 | 439 |
| 2018 | 333 |
| 2019 | 294 |
| 2020 | 309 |
| 2021 | 342 |
| 2022 | 307 |
| 2023 | 237 |
| 2024 | 228 |