| Year | Count |
|---|---|
| 1978 | 7 |
| 1979 | 24 |
| 1980 | 17 |
| 1981 | 35 |
| 1982 | 28 |
| 1983 | 37 |
| 1984 | 22 |
| 1985 | 16 |
| 1986 | 22 |
| 1987 | 43 |
| 1988 | 47 |
| 1989 | 81 |
| 1990 | 79 |
| 1991 | 95 |
| 1992 | 99 |
| 1993 | 141 |
| 1994 | 134 |
| 1995 | 149 |
| 1996 | 170 |
| 1997 | 102 |
| 1998 | 132 |
| 1999 | 79 |
| 2000 | 79 |
| 2001 | 60 |
| 2002 | 51 |
| 2003 | 93 |
| 2004 | 92 |
| 2005 | 37 |
| 2006 | 52 |
| 2007 | 78 |
| 2008 | 77 |
| 2009 | 42 |
| 2010 | 51 |
| 2011 | 31 |
| 2012 | 10 |
| 2016 | 14 |
| 2017 | 6 |
| 2018 | 13 |
| 2021 | 7 |