| Year | Count |
|---|---|
| 1964 | 6 |
| 1968 | 7 |
| 1969 | 7 |
| 1970 | 9 |
| 1972 | 5 |
| 1975 | 6 |
| 1976 | 14 |
| 1977 | 18 |
| 1978 | 18 |
| 1981 | 13 |
| 1982 | 15 |
| 1983 | 10 |
| 1984 | 11 |
| 1985 | 12 |
| 1986 | 30 |
| 1987 | 20 |
| 1988 | 32 |
| 1989 | 28 |
| 1990 | 53 |
| 1991 | 52 |
| 1992 | 102 |
| 1993 | 261 |
| 1994 | 125 |
| 1995 | 96 |
| 1996 | 74 |
| 1997 | 76 |
| 1998 | 59 |
| 1999 | 48 |
| 2000 | 56 |
| 2001 | 44 |
| 2002 | 50 |
| 2003 | 31 |
| 2004 | 34 |
| 2005 | 24 |
| 2006 | 17 |
| 2007 | 17 |
| 2008 | 24 |
| 2009 | 18 |
| 2010 | 17 |
| 2011 | 16 |
| 2012 | 20 |
| 2013 | 12 |
| 2014 | 16 |
| 2015 | 30 |
| 2016 | 30 |
| 2017 | 42 |
| 2018 | 20 |
| 2019 | 24 |
| 2021 | 7 |
| 2022 | 22 |