| Year | Count |
|---|---|
| 1975 | 10 |
| 1976 | 5 |
| 1977 | 22 |
| 1978 | 21 |
| 1979 | 33 |
| 1980 | 48 |
| 1981 | 32 |
| 1983 | 12 |
| 1984 | 5 |
| 1985 | 23 |
| 1986 | 10 |
| 1987 | 10 |
| 1989 | 5 |
| 1990 | 65 |
| 1991 | 105 |
| 1992 | 217 |
| 1993 | 266 |
| 1994 | 212 |
| 1995 | 160 |
| 1996 | 184 |
| 1997 | 125 |
| 1998 | 169 |
| 1999 | 106 |
| 2000 | 126 |
| 2001 | 85 |
| 2002 | 54 |
| 2003 | 27 |
| 2004 | 89 |
| 2005 | 115 |
| 2006 | 112 |
| 2007 | 148 |
| 2008 | 112 |
| 2009 | 143 |
| 2010 | 108 |
| 2011 | 88 |
| 2012 | 108 |
| 2013 | 74 |
| 2014 | 69 |
| 2015 | 81 |
| 2016 | 51 |
| 2017 | 18 |
| 2018 | 10 |
| 2019 | 20 |
| 2020 | 46 |
| 2021 | 20 |
| 2023 | 8 |