| Year | Count |
|---|---|
| 1967 | 5 |
| 1971 | 15 |
| 1972 | 8 |
| 1974 | 11 |
| 1975 | 8 |
| 1976 | 6 |
| 1977 | 5 |
| 1978 | 10 |
| 1980 | 12 |
| 1981 | 5 |
| 1982 | 5 |
| 1983 | 5 |
| 1985 | 6 |
| 1986 | 6 |
| 1987 | 36 |
| 1988 | 40 |
| 1989 | 174 |
| 1990 | 16 |
| 1991 | 21 |
| 1992 | 30 |
| 1993 | 56 |
| 1994 | 52 |
| 1995 | 52 |
| 1996 | 60 |
| 1997 | 85 |
| 1998 | 109 |
| 1999 | 260 |
| 2000 | 230 |
| 2001 | 263 |
| 2002 | 172 |
| 2003 | 142 |
| 2004 | 152 |
| 2005 | 140 |
| 2006 | 106 |
| 2007 | 169 |
| 2008 | 150 |
| 2009 | 64 |
| 2010 | 91 |
| 2011 | 51 |
| 2012 | 17 |
| 2013 | 27 |
| 2014 | 41 |
| 2015 | 6 |
| 2017 | 5 |
| 2019 | 16 |
| 2023 | 6 |