| Year | Count |
|---|---|
| 1969 | 13 |
| 1970 | 20 |
| 1971 | 32 |
| 1972 | 47 |
| 1973 | 74 |
| 1974 | 74 |
| 1975 | 70 |
| 1976 | 102 |
| 1977 | 160 |
| 1978 | 150 |
| 1979 | 178 |
| 1980 | 224 |
| 1981 | 85 |
| 1982 | 77 |
| 1983 | 72 |
| 1984 | 66 |
| 1985 | 81 |
| 1986 | 68 |
| 1987 | 53 |
| 1988 | 54 |
| 1989 | 40 |
| 1990 | 35 |
| 1991 | 27 |
| 1992 | 19 |
| 1993 | 21 |
| 1994 | 18 |
| 1995 | 13 |
| 1996 | 10 |
| 1997 | 6 |
| 1998 | 6 |
| 2001 | 5 |