| Year | Count |
|---|---|
| 1975 | 7 |
| 1977 | 18 |
| 1978 | 29 |
| 1980 | 5 |
| 1981 | 18 |
| 1982 | 11 |
| 1983 | 17 |
| 1984 | 10 |
| 1985 | 32 |
| 1986 | 16 |
| 1987 | 20 |
| 1988 | 25 |
| 1989 | 5 |
| 1990 | 6 |
| 1991 | 54 |
| 1992 | 21 |
| 1993 | 38 |
| 1994 | 52 |
| 1995 | 45 |
| 1996 | 41 |
| 1997 | 66 |
| 1998 | 88 |
| 1999 | 118 |
| 2000 | 164 |
| 2001 | 150 |
| 2002 | 100 |
| 2003 | 85 |
| 2004 | 98 |
| 2005 | 54 |
| 2006 | 64 |
| 2007 | 39 |
| 2008 | 72 |
| 2009 | 18 |
| 2010 | 23 |
| 2011 | 10 |
| 2012 | 5 |
| 2013 | 12 |
| 2014 | 6 |