| Year | Count |
|---|---|
| 1937 | 8 |
| 1938 | 12 |
| 1939 | 7 |
| 1940 | 12 |
| 1941 | 19 |
| 1942 | 30 |
| 1943 | 35 |
| 1944 | 31 |
| 1945 | 27 |
| 1946 | 31 |
| 1947 | 33 |
| 1948 | 28 |
| 1949 | 18 |
| 1950 | 18 |
| 1951 | 15 |
| 1952 | 13 |
| 1953 | 13 |
| 1954 | 14 |
| 1955 | 9 |
| 1956 | 16 |
| 1957 | 24 |
| 1958 | 26 |
| 1959 | 22 |
| 1960 | 32 |
| 1961 | 24 |
| 1962 | 7 |
| 1963 | 11 |
| 1964 | 14 |
| 1965 | 10 |
| 1966 | 11 |
| 1967 | 7 |
| 1968 | 12 |
| 1969 | 11 |
| 1970 | 13 |
| 1972 | 10 |
| 1974 | 9 |
| 1975 | 8 |
| 1977 | 14 |
| 1978 | 16 |
| 1979 | 12 |
| 1979 | 5 |
| 1981 | 8 |