| Year | Count |
|---|---|
| 1955 | 15 |
| 1956 | 19 |
| 1957 | 46 |
| 1958 | 37 |
| 1959 | 75 |
| 1960 | 63 |
| 1961 | 82 |
| 1962 | 76 |
| 1963 | 94 |
| 1964 | 228 |
| 1965 | 116 |
| 1966 | 110 |
| 1967 | 201 |
| 1968 | 309 |
| 1969 | 321 |
| 1970 | 380 |
| 1971 | 423 |
| 1972 | 377 |
| 1973 | 317 |
| 1974 | 345 |
| 1975 | 413 |
| 1976 | 304 |
| 1977 | 281 |
| 1978 | 192 |
| 1979 | 226 |
| 1980 | 139 |
| 1981 | 148 |
| 1982 | 101 |
| 1983 | 109 |
| 1984 | 144 |
| 1985 | 161 |
| 1986 | 121 |
| 1987 | 52 |
| 1988 | 65 |
| 1989 | 94 |
| 1990 | 26 |
| 1991 | 52 |
| 1992 | 21 |
| 1993 | 21 |
| 1994 | 31 |
| 1995 | 6 |
| 1997 | 6 |