| Year | Count |
|---|---|
| 1971 | 5 |
| 1972 | 6 |
| 1973 | 25 |
| 1974 | 19 |
| 1975 | 50 |
| 1976 | 64 |
| 1977 | 67 |
| 1978 | 81 |
| 1979 | 109 |
| 1980 | 108 |
| 1981 | 94 |
| 1982 | 99 |
| 1983 | 89 |
| 1984 | 50 |
| 1985 | 86 |
| 1986 | 85 |
| 1987 | 95 |
| 1988 | 105 |
| 1989 | 104 |
| 1990 | 150 |
| 1991 | 186 |
| 1992 | 257 |
| 1993 | 142 |
| 1994 | 109 |
| 1995 | 130 |
| 1996 | 153 |
| 1997 | 160 |
| 1998 | 204 |
| 1999 | 139 |
| 2000 | 135 |
| 2001 | 136 |
| 2002 | 95 |
| 2003 | 74 |
| 2004 | 118 |
| 2005 | 90 |
| 2006 | 110 |
| 2007 | 68 |
| 2008 | 105 |
| 2009 | 79 |
| 2010 | 72 |
| 2011 | 55 |
| 2012 | 51 |
| 2013 | 56 |
| 2014 | 46 |
| 2015 | 41 |
| 2016 | 41 |
| 2017 | 44 |
| 2018 | 26 |
| 2019 | 42 |
| 2020 | 15 |
| 2021 | 10 |
| 2023 | 10 |