| Year | Count |
|---|---|
| 1978 | 25 |
| 1979 | 5 |
| 1980 | 15 |
| 1981 | 15 |
| 1982 | 25 |
| 1983 | 7 |
| 1984 | 28 |
| 1985 | 48 |
| 1986 | 43 |
| 1987 | 46 |
| 1988 | 43 |
| 1989 | 78 |
| 1990 | 74 |
| 1991 | 137 |
| 1992 | 244 |
| 1993 | 152 |
| 1994 | 117 |
| 1995 | 99 |
| 1996 | 125 |
| 1997 | 68 |
| 1998 | 78 |
| 1999 | 72 |
| 2000 | 48 |
| 2001 | 56 |
| 2002 | 29 |
| 2003 | 22 |
| 2005 | 48 |
| 2006 | 20 |
| 2007 | 5 |
| 2008 | 17 |
| 2009 | 12 |
| 2010 | 5 |
| 2011 | 10 |
| 2013 | 10 |
| 2014 | 12 |
| 2015 | 6 |
| 2017 | 5 |