| Year | Count |
|---|---|
| 1957 | 6 |
| 1958 | 10 |
| 1959 | 35 |
| 1960 | 5 |
| 1961 | 41 |
| 1962 | 36 |
| 1963 | 44 |
| 1964 | 66 |
| 1965 | 104 |
| 1966 | 258 |
| 1967 | 272 |
| 1968 | 300 |
| 1969 | 245 |
| 1970 | 219 |
| 1971 | 218 |
| 1972 | 120 |
| 1973 | 107 |
| 1974 | 101 |
| 1975 | 79 |
| 1976 | 5 |
| 1977 | 29 |
| 1978 | 38 |
| 1979 | 56 |
| 1980 | 5 |
| 1981 | 15 |
| 1982 | 17 |
| 1983 | 5 |
| 1984 | 15 |
| 1985 | 10 |
| 1987 | 30 |
| 1988 | 28 |
| 1990 | 61 |
| 1991 | 7 |
| 1992 | 20 |