| Year | Count |
|---|---|
| 1930 | 9 |
| 1931 | 7 |
| 1932 | 6 |
| 1933 | 10 |
| 1934 | 6 |
| 1935 | 16 |
| 1936 | 14 |
| 1937 | 13 |
| 1938 | 17 |
| 1939 | 17 |
| 1940 | 21 |
| 1941 | 40 |
| 1942 | 29 |
| 1943 | 35 |
| 1944 | 35 |
| 1945 | 36 |
| 1946 | 62 |
| 1947 | 46 |
| 1948 | 77 |
| 1949 | 94 |
| 1950 | 69 |
| 1951 | 80 |
| 1952 | 64 |
| 1953 | 85 |
| 1954 | 92 |
| 1955 | 56 |
| 1956 | 76 |
| 1957 | 88 |
| 1958 | 95 |
| 1959 | 114 |
| 1960 | 58 |
| 1961 | 53 |
| 1962 | 41 |
| 1963 | 39 |
| 1964 | 41 |
| 1965 | 50 |
| 1966 | 36 |
| 1967 | 17 |
| 1968 | 35 |
| 1969 | 21 |
| 1970 | 11 |
| 1971 | 10 |
| 1972 | 14 |
| 1973 | 20 |
| 1974 | 10 |
| 1975 | 10 |
| 1976 | 5 |
| 1977 | 5 |