| Year | Count |
|---|---|
| 1972 | 6 |
| 1973 | 8 |
| 1974 | 5 |
| 1975 | 26 |
| 1976 | 15 |
| 1977 | 6 |
| 1978 | 6 |
| 1979 | 5 |
| 1980 | 5 |
| 1981 | 28 |
| 1982 | 33 |
| 1983 | 17 |
| 1984 | 11 |
| 1985 | 32 |
| 1986 | 26 |
| 1987 | 23 |
| 1988 | 18 |
| 1989 | 30 |
| 1990 | 35 |
| 1991 | 35 |
| 1992 | 16 |
| 1993 | 57 |
| 1994 | 37 |
| 1995 | 41 |
| 1996 | 49 |
| 1997 | 60 |
| 1998 | 54 |
| 1999 | 22 |
| 2001 | 16 |
| 2002 | 12 |
| 2003 | 10 |
| 2005 | 5 |
| 2006 | 10 |
| 2009 | 10 |
| 2011 | 6 |