| Year | Count |
|---|---|
| 1971 | 5 |
| 1972 | 10 |
| 1973 | 6 |
| 1974 | 6 |
| 1978 | 12 |
| 1979 | 5 |
| 1980 | 10 |
| 1983 | 6 |
| 1984 | 5 |
| 1985 | 16 |
| 1986 | 29 |
| 1987 | 35 |
| 1988 | 55 |
| 1989 | 80 |
| 1990 | 72 |
| 1991 | 23 |
| 1991 | 115 |
| 1992 | 35 |
| 1992 | 86 |
| 1993 | 124 |
| 1994 | 121 |
| 1995 | 16 |
| 1995 | 64 |
| 1996 | 12 |
| 1996 | 35 |
| 1997 | 32 |
| 1997 | 47 |
| 1998 | 5 |
| 1998 | 111 |
| 1999 | 87 |
| 2000 | 36 |
| 2001 | 6 |
| 2001 | 77 |
| 2002 | 8 |
| 2002 | 9 |
| 2003 | 6 |
| 2003 | 83 |
| 2004 | 16 |
| 2004 | 55 |
| 2005 | 5 |
| 2005 | 29 |
| 2006 | 6 |
| 2006 | 17 |
| 2007 | 7 |
| 2007 | 35 |
| 2008 | 61 |
| 2009 | 6 |
| 2010 | 8 |
| 2010 | 20 |
| 2011 | 6 |
| 2011 | 28 |
| 2012 | 5 |
| 2012 | 10 |
| 2013 | 5 |
| 2014 | 16 |
| 2018 | 5 |