| Year | Count |
|---|---|
| 1975 | 14 |
| 1976 | 18 |
| 1977 | 5 |
| 1979 | 5 |
| 1981 | 5 |
| 1984 | 12 |
| 1985 | 10 |
| 1986 | 16 |
| 1987 | 28 |
| 1988 | 7 |
| 1989 | 17 |
| 1990 | 33 |
| 1991 | 19 |
| 1992 | 5 |
| 1993 | 24 |
| 1994 | 18 |
| 1995 | 8 |
| 1996 | 7 |
| 1998 | 32 |
| 1999 | 152 |
| 2000 | 108 |
| 2001 | 63 |
| 2002 | 44 |
| 2003 | 66 |
| 2004 | 51 |
| 2005 | 10 |
| 2006 | 34 |
| 2007 | 28 |
| 2008 | 17 |
| 2009 | 10 |
| 2010 | 15 |
| 2011 | 30 |
| 2012 | 14 |
| 2014 | 10 |
| 2017 | 10 |