| Year | Count |
|---|---|
| 1975 | 5 |
| 1977 | 24 |
| 1978 | 41 |
| 1979 | 63 |
| 1980 | 68 |
| 1981 | 77 |
| 1982 | 51 |
| 1983 | 79 |
| 1984 | 85 |
| 1985 | 92 |
| 1986 | 58 |
| 1987 | 109 |
| 1988 | 101 |
| 1989 | 126 |
| 1990 | 128 |
| 1991 | 142 |
| 1992 | 160 |
| 1993 | 129 |
| 1994 | 90 |
| 1995 | 112 |
| 1996 | 47 |
| 1997 | 47 |
| 1998 | 14 |
| 1999 | 58 |
| 2000 | 37 |
| 2001 | 35 |
| 2002 | 34 |
| 2003 | 16 |
| 2004 | 18 |
| 2005 | 46 |
| 2006 | 29 |
| 2007 | 34 |
| 2008 | 17 |
| 2009 | 19 |
| 2010 | 20 |
| 2011 | 25 |
| 2012 | 35 |
| 2013 | 19 |
| 2014 | 19 |
| 2015 | 31 |
| 2016 | 21 |
| 2018 | 5 |
| 2019 | 10 |
| 2020 | 5 |