| Year | Count |
|---|---|
| 1957 | 28 |
| 1958 | 27 |
| 1959 | 28 |
| 1960 | 44 |
| 1961 | 41 |
| 1962 | 56 |
| 1963 | 52 |
| 1964 | 44 |
| 1965 | 30 |
| 1966 | 81 |
| 1967 | 145 |
| 1968 | 133 |
| 1969 | 175 |
| 1970 | 242 |
| 1971 | 248 |
| 1972 | 242 |
| 1973 | 237 |
| 1974 | 273 |
| 1975 | 335 |
| 1976 | 215 |
| 1977 | 214 |
| 1978 | 212 |
| 1979 | 196 |
| 1980 | 120 |
| 1981 | 103 |
| 1982 | 17 |
| 1983 | 36 |
| 1984 | 24 |
| 1985 | 42 |
| 1986 | 15 |
| 1988 | 12 |