| Year | Count |
|---|---|
| 1956 | 6 |
| 1957 | 7 |
| 1958 | 5 |
| 1959 | 10 |
| 1960 | 5 |
| 1961 | 11 |
| 1962 | 5 |
| 1964 | 7 |
| 1966 | 6 |
| 1968 | 6 |
| 1969 | 15 |
| 1970 | 15 |
| 1971 | 41 |
| 1972 | 28 |
| 1973 | 22 |
| 1974 | 26 |
| 1975 | 29 |
| 1976 | 53 |
| 1978 | 18 |
| 1979 | 11 |
| 1981 | 5 |
| 1985 | 5 |
| 1987 | 20 |
| 1988 | 5 |
| 1989 | 12 |
| 1990 | 103 |
| 1991 | 98 |
| 1992 | 159 |
| 1993 | 124 |
| 1994 | 57 |
| 1995 | 65 |
| 1996 | 68 |
| 1997 | 56 |
| 1998 | 85 |
| 1999 | 26 |
| 2000 | 5 |
| 2001 | 12 |
| 2002 | 20 |
| 2007 | 5 |