| Year | Count |
|---|---|
| 1987 | 12 |
| 1988 | 10 |
| 1989 | 11 |
| 1990 | 20 |
| 1991 | 19 |
| 1992 | 21 |
| 1993 | 19 |
| 1994 | 17 |
| 1995 | 20 |
| 1996 | 23 |
| 1997 | 23 |
| 1998 | 28 |
| 1999 | 18 |
| 2000 | 28 |
| 2001 | 36 |
| 2002 | 30 |
| 2003 | 26 |
| 2004 | 18 |
| 2005 | 23 |
| 2006 | 18 |
| 2007 | 19 |
| 2008 | 16 |
| 2009 | 18 |
| 2010 | 16 |
| 2011 | 18 |
| 2012 | 11 |
| 2013 | 18 |
| 2014 | 19 |
| 2015 | 36 |
| 2016 | 18 |
| 2018 | 12 |
| 2019 | 10 |
| 2021 | 16 |