| Year | Count |
|---|---|
| 1956 | 5 |
| 1957 | 10 |
| 1959 | 12 |
| 1960 | 6 |
| 1961 | 23 |
| 1962 | 10 |
| 1963 | 15 |
| 1964 | 5 |
| 1965 | 29 |
| 1966 | 19 |
| 1967 | 61 |
| 1968 | 25 |
| 1969 | 86 |
| 1970 | 69 |
| 1971 | 93 |
| 1972 | 92 |
| 1973 | 92 |
| 1974 | 64 |
| 1975 | 55 |
| 1976 | 69 |
| 1977 | 76 |
| 1978 | 61 |
| 1979 | 94 |
| 1980 | 48 |
| 1981 | 75 |
| 1982 | 66 |
| 1983 | 166 |
| 1984 | 82 |
| 1985 | 131 |
| 1986 | 88 |
| 1987 | 114 |
| 1988 | 99 |
| 1989 | 58 |
| 1990 | 54 |
| 1991 | 12 |
| 1992 | 15 |
| 1993 | 13 |
| 1994 | 9 |
| 1995 | 7 |
| 1996 | 13 |
| 1997 | 5 |