| Year | Count |
|---|---|
| 1975 | 8 |
| 1976 | 6 |
| 1977 | 13 |
| 1978 | 12 |
| 1979 | 11 |
| 1980 | 22 |
| 1981 | 12 |
| 1981 | 31 |
| 1982 | 14 |
| 1983 | 6 |
| 1984 | 20 |
| 1985 | 36 |
| 1987 | 10 |
| 1988 | 21 |
| 1989 | 52 |
| 1990 | 48 |
| 1991 | 63 |
| 1992 | 49 |
| 1993 | 76 |
| 1994 | 85 |
| 1995 | 129 |
| 1996 | 119 |
| 1997 | 161 |
| 1998 | 149 |
| 1999 | 170 |
| 2000 | 263 |
| 2001 | 263 |
| 2002 | 266 |
| 2003 | 235 |
| 2004 | 270 |
| 2005 | 233 |
| 2006 | 248 |
| 2007 | 223 |
| 2008 | 251 |
| 2009 | 212 |
| 2010 | 206 |
| 2011 | 221 |
| 2012 | 174 |
| 2013 | 143 |
| 2014 | 125 |
| 2015 | 98 |
| 2016 | 113 |
| 2017 | 65 |
| 2018 | 74 |
| 2020 | 39 |
| 2021 | 41 |
| 2022 | 37 |
| 2023 | 43 |
| 2024 | 35 |