| Year | Count |
|---|---|
| 1968 | 7 |
| 1970 | 6 |
| 1972 | 5 |
| 1973 | 6 |
| 1974 | 5 |
| 1975 | 12 |
| 1976 | 13 |
| 1977 | 50 |
| 1978 | 64 |
| 1979 | 40 |
| 1980 | 46 |
| 1981 | 32 |
| 1982 | 14 |
| 1983 | 28 |
| 1984 | 21 |
| 1985 | 45 |
| 1986 | 34 |
| 1987 | 41 |
| 1988 | 39 |
| 1989 | 34 |
| 1990 | 33 |
| 1991 | 27 |
| 1992 | 30 |
| 1993 | 21 |
| 1994 | 14 |
| 1995 | 12 |
| 1996 | 7 |
| 1997 | 8 |
| 1998 | 6 |
| 1999 | 5 |
| 2000 | 6 |
| 2003 | 8 |