| Year | Count |
|---|---|
| 1968 | 10 |
| 1969 | 21 |
| 1970 | 15 |
| 1971 | 58 |
| 1972 | 72 |
| 1973 | 85 |
| 1974 | 122 |
| 1975 | 113 |
| 1976 | 105 |
| 1977 | 186 |
| 1978 | 176 |
| 1979 | 210 |
| 1980 | 152 |
| 1981 | 85 |
| 1982 | 77 |
| 1983 | 71 |
| 1984 | 62 |
| 1985 | 54 |
| 1986 | 64 |
| 1987 | 60 |
| 1988 | 46 |
| 1989 | 59 |
| 1990 | 59 |
| 1991 | 45 |
| 1992 | 55 |
| 1993 | 35 |
| 1994 | 31 |
| 1995 | 27 |
| 1996 | 20 |
| 1997 | 10 |
| 1998 | 8 |
| 2000 | 7 |