| Year | Count |
|---|---|
| 1970 | 6 |
| 1971 | 8 |
| 1973 | 8 |
| 1975 | 7 |
| 1976 | 5 |
| 1977 | 7 |
| 1978 | 9 |
| 1979 | 8 |
| 1980 | 13 |
| 1981 | 11 |
| 1982 | 14 |
| 1983 | 15 |
| 1984 | 10 |
| 1985 | 16 |
| 1986 | 14 |
| 1987 | 15 |
| 1988 | 16 |
| 1989 | 25 |
| 1990 | 28 |
| 1991 | 17 |
| 1992 | 20 |
| 1993 | 34 |
| 1994 | 16 |
| 1995 | 30 |
| 1996 | 27 |
| 1997 | 36 |
| 1998 | 37 |
| 1999 | 41 |
| 2000 | 50 |
| 2001 | 38 |
| 2002 | 59 |
| 2003 | 47 |
| 2004 | 51 |
| 2005 | 52 |
| 2006 | 58 |
| 2007 | 73 |
| 2008 | 71 |
| 2009 | 75 |
| 2010 | 78 |
| 2011 | 75 |
| 2012 | 79 |
| 2013 | 87 |
| 2014 | 85 |
| 2015 | 105 |
| 2016 | 145 |
| 2017 | 143 |
| 2018 | 161 |
| 2019 | 158 |
| 2020 | 112 |
| 2021 | 128 |
| 2022 | 154 |
| 2023 | 136 |
| 2024 | 131 |