| Year | Count |
|---|---|
| 1973 | 7 |
| 1974 | 5 |
| 1975 | 6 |
| 1976 | 10 |
| 1977 | 5 |
| 1978 | 6 |
| 1979 | 34 |
| 1980 | 42 |
| 1981 | 50 |
| 1982 | 18 |
| 1983 | 61 |
| 1984 | 107 |
| 1985 | 156 |
| 1986 | 179 |
| 1987 | 382 |
| 1988 | 501 |
| 1989 | 581 |
| 1990 | 602 |
| 1991 | 651 |
| 1992 | 547 |
| 1993 | 535 |
| 1994 | 393 |
| 1995 | 347 |
| 1996 | 333 |
| 1997 | 252 |
| 1998 | 238 |
| 1999 | 151 |
| 2000 | 199 |
| 2001 | 146 |
| 2002 | 127 |
| 2003 | 95 |
| 2004 | 189 |
| 2005 | 128 |
| 2006 | 101 |
| 2007 | 44 |
| 2008 | 83 |
| 2009 | 36 |
| 2010 | 81 |
| 2011 | 55 |
| 2012 | 43 |
| 2013 | 15 |
| 2014 | 18 |
| 2015 | 47 |
| 2016 | 12 |
| 2017 | 20 |
| 2018 | 29 |
| 2019 | 7 |
| 2020 | 40 |
| 2021 | 17 |
| 2022 | 16 |
| 2023 | 27 |
| 2024 | 32 |