| Year | Count |
|---|---|
| 1947 | 5 |
| 1948 | 5 |
| 1949 | 6 |
| 1950 | 7 |
| 1951 | 5 |
| 1952 | 11 |
| 1953 | 18 |
| 1954 | 15 |
| 1955 | 15 |
| 1956 | 20 |
| 1957 | 80 |
| 1958 | 78 |
| 1959 | 94 |
| 1960 | 100 |
| 1961 | 134 |
| 1963 | 56 |
| 1964 | 62 |
| 1965 | 40 |
| 1966 | 34 |
| 1967 | 37 |
| 1968 | 33 |
| 1969 | 31 |
| 1970 | 29 |
| 1971 | 28 |
| 1972 | 17 |
| 1973 | 15 |
| 1974 | 9 |
| 1975 | 7 |
| 1976 | 8 |
| 1977 | 20 |
| 1978 | 10 |
| 1979 | 10 |
| 1982 | 8 |
| 1983 | 7 |
| 1985 | 6 |
| 1986 | 5 |
| 1987 | 5 |
| 1991 | 6 |