| Year | Count |
|---|---|
| 1957 | 6 |
| 1958 | 5 |
| 1959 | 18 |
| 1960 | 51 |
| 1961 | 88 |
| 1962 | 174 |
| 1963 | 202 |
| 1964 | 277 |
| 1965 | 377 |
| 1966 | 415 |
| 1967 | 619 |
| 1968 | 780 |
| 1969 | 990 |
| 1970 | 1,238 |
| 1971 | 1,539 |
| 1972 | 1,568 |
| 1973 | 1,502 |
| 1974 | 1,644 |
| 1975 | 1,541 |
| 1976 | 1,301 |
| 1977 | 1,232 |
| 1978 | 1,219 |
| 1979 | 1,210 |
| 1980 | 1,210 |
| 1981 | 1,311 |
| 1982 | 919 |
| 1983 | 782 |
| 1984 | 825 |
| 1985 | 729 |
| 1986 | 581 |
| 1987 | 468 |
| 1988 | 392 |
| 1989 | 326 |
| 1989 | 5 |
| 1990 | 279 |
| 1991 | 256 |
| 1992 | 156 |
| 1993 | 174 |
| 1994 | 56 |
| 1995 | 39 |
| 1996 | 30 |
| 1997 | 30 |
| 1999 | 37 |
| 2000 | 20 |
| 2002 | 5 |
| 2003 | 10 |
| 2004 | 5 |