| Year | Count |
|---|---|
| 1975 | 6 |
| 1977 | 12 |
| 1979 | 29 |
| 1981 | 10 |
| 1983 | 10 |
| 1984 | 32 |
| 1985 | 10 |
| 1986 | 40 |
| 1987 | 61 |
| 1988 | 37 |
| 1989 | 63 |
| 1990 | 80 |
| 1991 | 113 |
| 1992 | 100 |
| 1993 | 132 |
| 1994 | 93 |
| 1995 | 107 |
| 1996 | 62 |
| 1997 | 50 |
| 1998 | 64 |
| 1999 | 24 |
| 2000 | 39 |
| 2001 | 22 |
| 2002 | 17 |
| 2003 | 20 |
| 2004 | 41 |
| 2005 | 34 |
| 2006 | 17 |
| 2007 | 13 |
| 2008 | 12 |
| 2009 | 5 |