| Year | Count |
|---|---|
| 1961 | 5 |
| 1962 | 5 |
| 1964 | 6 |
| 1965 | 11 |
| 1966 | 13 |
| 1967 | 25 |
| 1968 | 46 |
| 1969 | 29 |
| 1970 | 87 |
| 1971 | 105 |
| 1972 | 101 |
| 1973 | 120 |
| 1974 | 119 |
| 1975 | 119 |
| 1976 | 160 |
| 1977 | 119 |
| 1978 | 199 |
| 1979 | 216 |
| 1980 | 215 |
| 1981 | 279 |
| 1982 | 251 |
| 1983 | 193 |
| 1984 | 140 |
| 1985 | 186 |
| 1986 | 120 |
| 1987 | 158 |
| 1988 | 99 |
| 1989 | 90 |
| 1990 | 81 |
| 1991 | 48 |
| 1992 | 34 |
| 1993 | 10 |