| Year | Count |
|---|---|
| 1971 | 5 |
| 1974 | 6 |
| 1976 | 12 |
| 1977 | 7 |
| 1978 | 36 |
| 1979 | 20 |
| 1980 | 52 |
| 1981 | 54 |
| 1982 | 62 |
| 1983 | 66 |
| 1984 | 69 |
| 1985 | 116 |
| 1986 | 81 |
| 1987 | 96 |
| 1988 | 80 |
| 1989 | 123 |
| 1990 | 180 |
| 1991 | 161 |
| 1992 | 168 |
| 1993 | 164 |
| 1994 | 78 |
| 1995 | 102 |
| 1996 | 207 |
| 1997 | 186 |
| 1998 | 159 |
| 1999 | 124 |
| 2000 | 125 |
| 2001 | 119 |
| 2002 | 144 |
| 2003 | 158 |
| 2004 | 151 |
| 2005 | 129 |
| 2006 | 145 |
| 2007 | 137 |
| 2008 | 136 |
| 2009 | 119 |
| 2010 | 98 |
| 2011 | 123 |
| 2012 | 86 |
| 2013 | 48 |
| 2014 | 67 |
| 2015 | 79 |
| 2016 | 31 |
| 2017 | 69 |
| 2018 | 21 |
| 2019 | 6 |
| 2020 | 11 |
| 2022 | 26 |
| 2023 | 6 |
| 2024 | 11 |