| Year | Count |
|---|---|
| 1937 | 21 |
| 1938 | 54 |
| 1939 | 25 |
| 1940 | 24 |
| 1941 | 35 |
| 1942 | 47 |
| 1943 | 19 |
| 1944 | 23 |
| 1945 | 12 |
| 1946 | 25 |
| 1947 | 48 |
| 1948 | 34 |
| 1949 | 43 |
| 1950 | 39 |
| 1951 | 66 |
| 1952 | 104 |
| 1953 | 111 |
| 1954 | 170 |
| 1955 | 148 |
| 1956 | 193 |
| 1957 | 194 |
| 1958 | 238 |
| 1959 | 316 |
| 1960 | 364 |
| 1961 | 441 |
| 1962 | 513 |
| 1963 | 429 |
| 1964 | 385 |
| 1965 | 422 |
| 1966 | 388 |
| 1967 | 464 |
| 1968 | 456 |
| 1969 | 492 |
| 1970 | 446 |
| 1971 | 405 |
| 1972 | 309 |
| 1973 | 181 |
| 1974 | 214 |
| 1975 | 123 |
| 1976 | 146 |
| 1977 | 126 |
| 1978 | 107 |
| 1979 | 53 |
| 1980 | 135 |
| 1981 | 83 |
| 1982 | 34 |
| 1983 | 50 |
| 1984 | 29 |
| 1985 | 73 |
| 1986 | 18 |
| 1987 | 26 |
| 1988 | 20 |
| 1989 | 10 |
| 1990 | 10 |
| 1997 | 5 |