| Year | Count |
|---|---|
| 1981 | 11 |
| 1986 | 14 |
| 1987 | 15 |
| 1988 | 10 |
| 1989 | 18 |
| 1990 | 56 |
| 1991 | 53 |
| 1992 | 34 |
| 1993 | 60 |
| 1994 | 58 |
| 1995 | 54 |
| 1996 | 13 |
| 1997 | 10 |
| 1998 | 29 |
| 1999 | 35 |
| 2000 | 26 |
| 2001 | 42 |
| 2002 | 10 |
| 2003 | 48 |
| 2004 | 71 |
| 2005 | 36 |
| 2006 | 114 |
| 2007 | 35 |
| 2008 | 6 |
| 2009 | 32 |
| 2010 | 28 |
| 2011 | 20 |
| 2012 | 5 |
| 2013 | 22 |
| 2014 | 20 |
| 2015 | 22 |
| 2016 | 5 |
| 2018 | 10 |