| Year | Count |
|---|---|
| 1969 | 7 |
| 1970 | 5 |
| 1972 | 11 |
| 1973 | 12 |
| 1974 | 6 |
| 1975 | 18 |
| 1976 | 18 |
| 1977 | 68 |
| 1978 | 60 |
| 1979 | 62 |
| 1980 | 88 |
| 1981 | 39 |
| 1982 | 40 |
| 1983 | 41 |
| 1984 | 46 |
| 1985 | 43 |
| 1986 | 49 |
| 1987 | 39 |
| 1988 | 34 |
| 1989 | 26 |
| 1990 | 29 |
| 1991 | 25 |
| 1992 | 26 |
| 1993 | 19 |
| 1994 | 21 |
| 1995 | 20 |
| 1996 | 23 |
| 1997 | 13 |
| 1998 | 5 |
| 1999 | 6 |
| 2000 | 9 |
| 2001 | 7 |
| 2002 | 12 |
| 2003 | 9 |
| 2004 | 6 |
| 2005 | 5 |
| 2006 | 6 |
| 2009 | 5 |