| Year | Count |
|---|---|
| 1981 | 5 |
| 1983 | 5 |
| 1984 | 10 |
| 1986 | 5 |
| 1987 | 5 |
| 1989 | 5 |
| 1990 | 11 |
| 1991 | 11 |
| 1992 | 5 |
| 1993 | 11 |
| 1994 | 5 |
| 1995 | 17 |
| 1996 | 23 |
| 1997 | 31 |
| 1998 | 66 |
| 1999 | 17 |
| 2000 | 31 |
| 2001 | 42 |
| 2002 | 30 |
| 2003 | 54 |
| 2004 | 61 |
| 2005 | 73 |
| 2006 | 85 |
| 2007 | 76 |
| 2008 | 48 |
| 2009 | 65 |
| 2010 | 33 |
| 2011 | 15 |
| 2012 | 21 |
| 2013 | 12 |
| 2014 | 17 |
| 2015 | 20 |
| 2016 | 16 |
| 2018 | 10 |