| Year | Count |
|---|---|
| 1955 | 6 |
| 1956 | 5 |
| 1957 | 26 |
| 1958 | 10 |
| 1960 | 8 |
| 1961 | 27 |
| 1962 | 10 |
| 1963 | 34 |
| 1964 | 30 |
| 1965 | 73 |
| 1966 | 93 |
| 1967 | 121 |
| 1968 | 136 |
| 1969 | 209 |
| 1970 | 311 |
| 1971 | 341 |
| 1972 | 344 |
| 1973 | 415 |
| 1974 | 416 |
| 1975 | 390 |
| 1976 | 401 |
| 1977 | 425 |
| 1978 | 421 |
| 1979 | 354 |
| 1980 | 287 |
| 1981 | 276 |
| 1982 | 227 |
| 1983 | 207 |
| 1984 | 195 |
| 1985 | 249 |
| 1986 | 189 |
| 1987 | 182 |
| 1988 | 146 |
| 1989 | 69 |
| 1990 | 55 |
| 1991 | 56 |
| 1992 | 42 |
| 1993 | 52 |
| 1994 | 60 |
| 1996 | 10 |
| 1998 | 5 |