| Year | Count |
|---|---|
| 1955 | 5 |
| 1956 | 11 |
| 1957 | 16 |
| 1958 | 12 |
| 1959 | 24 |
| 1960 | 16 |
| 1961 | 7 |
| 1962 | 10 |
| 1963 | 7 |
| 1964 | 21 |
| 1965 | 9 |
| 1966 | 13 |
| 1967 | 18 |
| 1968 | 27 |
| 1969 | 24 |
| 1970 | 35 |
| 1971 | 29 |
| 1972 | 20 |
| 1973 | 19 |
| 1974 | 24 |
| 1975 | 40 |
| 1976 | 30 |
| 1977 | 24 |
| 1978 | 28 |
| 1979 | 40 |
| 1980 | 30 |
| 1981 | 21 |
| 1982 | 10 |
| 1983 | 11 |
| 1984 | 17 |
| 1985 | 13 |
| 1986 | 13 |
| 1987 | 11 |
| 1988 | 12 |
| 1989 | 11 |
| 1990 | 21 |
| 1991 | 9 |
| 1992 | 5 |
| 1994 | 6 |
| 1995 | 6 |