| Year | Count |
|---|---|
| 1956 | 5 |
| 1957 | 12 |
| 1958 | 14 |
| 1959 | 26 |
| 1960 | 16 |
| 1961 | 24 |
| 1962 | 8 |
| 1963 | 8 |
| 1964 | 15 |
| 1965 | 7 |
| 1966 | 16 |
| 1967 | 19 |
| 1968 | 19 |
| 1969 | 25 |
| 1970 | 15 |
| 1971 | 21 |
| 1972 | 14 |
| 1973 | 29 |
| 1974 | 17 |
| 1975 | 28 |
| 1976 | 35 |
| 1977 | 24 |
| 1978 | 34 |
| 1979 | 24 |
| 1981 | 17 |
| 1982 | 14 |
| 1983 | 11 |
| 1984 | 6 |
| 1985 | 6 |
| 1986 | 9 |
| 1987 | 7 |
| 1988 | 7 |
| 1989 | 8 |
| 1990 | 6 |
| 1991 | 9 |
| 1992 | 6 |
| 1993 | 10 |