| Year | Count |
|---|---|
| 1973 | 12 |
| 1978 | 20 |
| 1980 | 25 |
| 1981 | 6 |
| 1982 | 11 |
| 1984 | 12 |
| 1985 | 5 |
| 1986 | 17 |
| 1987 | 17 |
| 1988 | 26 |
| 1989 | 29 |
| 1990 | 41 |
| 1991 | 44 |
| 1992 | 51 |
| 1993 | 18 |
| 1994 | 10 |
| 1995 | 10 |
| 1996 | 32 |
| 1997 | 9 |
| 1998 | 31 |
| 1999 | 15 |
| 2000 | 12 |
| 2001 | 12 |
| 2004 | 16 |
| 2006 | 38 |
| 2007 | 23 |
| 2008 | 20 |
| 2010 | 27 |
| 2011 | 24 |
| 2013 | 5 |
| 2014 | 10 |