| Year | Count |
|---|---|
| 1978 | 15 |
| 1982 | 18 |
| 1983 | 12 |
| 1984 | 20 |
| 1986 | 10 |
| 1987 | 12 |
| 1988 | 12 |
| 1989 | 14 |
| 1990 | 27 |
| 1991 | 30 |
| 1992 | 23 |
| 1993 | 28 |
| 1994 | 28 |
| 1995 | 28 |
| 1996 | 17 |
| 1997 | 18 |
| 1998 | 12 |
| 1999 | 24 |
| 2000 | 16 |
| 2001 | 24 |
| 2002 | 24 |
| 2003 | 21 |
| 2004 | 29 |
| 2005 | 24 |
| 2006 | 32 |
| 2007 | 20 |
| 2008 | 29 |
| 2009 | 16 |
| 2010 | 6 |
| 2011 | 16 |
| 2013 | 12 |
| 2014 | 12 |
| 2015 | 14 |