| Year | Count |
|---|---|
| 1955 | 5 |
| 1956 | 22 |
| 1957 | 19 |
| 1958 | 66 |
| 1959 | 149 |
| 1960 | 165 |
| 1961 | 158 |
| 1962 | 160 |
| 1963 | 181 |
| 1964 | 150 |
| 1965 | 159 |
| 1966 | 115 |
| 1967 | 227 |
| 1968 | 268 |
| 1969 | 270 |
| 1970 | 335 |
| 1971 | 417 |
| 1972 | 371 |
| 1973 | 464 |
| 1974 | 421 |
| 1975 | 523 |
| 1976 | 428 |
| 1977 | 629 |
| 1978 | 433 |
| 1979 | 370 |
| 1980 | 228 |
| 1981 | 203 |
| 1982 | 248 |
| 1983 | 197 |
| 1984 | 125 |
| 1985 | 133 |
| 1986 | 116 |
| 1987 | 78 |
| 1988 | 99 |
| 1989 | 63 |
| 1990 | 40 |
| 1991 | 34 |
| 1992 | 47 |
| 1993 | 62 |
| 1994 | 5 |
| 1995 | 32 |
| 1996 | 12 |
| 1997 | 39 |
| 1999 | 17 |