| Year | Count |
|---|---|
| 1956 | 5 |
| 1958 | 6 |
| 1959 | 10 |
| 1960 | 6 |
| 1961 | 15 |
| 1962 | 20 |
| 1963 | 10 |
| 1964 | 14 |
| 1965 | 44 |
| 1966 | 48 |
| 1967 | 85 |
| 1968 | 100 |
| 1969 | 66 |
| 1970 | 119 |
| 1971 | 88 |
| 1972 | 68 |
| 1973 | 58 |
| 1974 | 68 |
| 1975 | 48 |
| 1976 | 40 |
| 1977 | 48 |
| 1978 | 55 |
| 1979 | 22 |
| 1980 | 19 |
| 1981 | 20 |
| 1982 | 29 |
| 1983 | 12 |
| 1984 | 15 |
| 1985 | 6 |
| 1986 | 10 |
| 1987 | 10 |
| 1988 | 11 |