| Year | Count |
|---|---|
| 1986 | 5 |
| 1988 | 7 |
| 1989 | 14 |
| 1990 | 10 |
| 1991 | 15 |
| 1992 | 12 |
| 1993 | 17 |
| 1994 | 23 |
| 1995 | 31 |
| 1996 | 17 |
| 1997 | 18 |
| 1998 | 29 |
| 1999 | 24 |
| 2000 | 31 |
| 2001 | 14 |
| 2002 | 15 |
| 2003 | 15 |
| 2004 | 16 |
| 2005 | 17 |
| 2006 | 21 |
| 2007 | 22 |
| 2008 | 20 |
| 2009 | 18 |
| 2010 | 7 |
| 2011 | 8 |
| 2012 | 15 |
| 2013 | 7 |
| 2015 | 15 |
| 2016 | 18 |
| 2017 | 21 |
| 2018 | 14 |