| Year | Count |
|---|---|
| 1957 | 20 |
| 1958 | 6 |
| 1981 | 21 |
| 1982 | 6 |
| 1983 | 7 |
| 1984 | 5 |
| 1985 | 24 |
| 1986 | 27 |
| 1987 | 32 |
| 1988 | 36 |
| 1989 | 46 |
| 1990 | 85 |
| 1991 | 100 |
| 1992 | 127 |
| 1993 | 127 |
| 1994 | 78 |
| 1995 | 48 |
| 1996 | 64 |
| 1997 | 46 |
| 1998 | 42 |
| 1999 | 42 |
| 2000 | 61 |
| 2001 | 24 |
| 2002 | 49 |
| 2003 | 59 |
| 2004 | 52 |
| 2005 | 20 |
| 2006 | 31 |
| 2007 | 7 |
| 2008 | 27 |
| 2009 | 42 |
| 2010 | 6 |
| 2011 | 36 |
| 2012 | 10 |
| 2014 | 13 |
| 2016 | 6 |
| 2017 | 10 |
| 2018 | 15 |
| 2019 | 19 |
| 2020 | 10 |