| Year | Count |
|---|---|
| 1956 | 15 |
| 1957 | 30 |
| 1959 | 10 |
| 1960 | 16 |
| 1961 | 5 |
| 1962 | 7 |
| 1963 | 6 |
| 1964 | 5 |
| 1966 | 8 |
| 1968 | 5 |
| 1969 | 6 |
| 1970 | 6 |
| 1971 | 14 |
| 1973 | 8 |
| 1974 | 13 |
| 1975 | 6 |
| 1976 | 10 |
| 1977 | 26 |
| 1978 | 28 |
| 1979 | 20 |
| 1980 | 13 |
| 1981 | 37 |
| 1982 | 90 |
| 1983 | 137 |
| 1984 | 203 |
| 1985 | 183 |
| 1986 | 74 |
| 1987 | 67 |
| 1988 | 53 |
| 1989 | 50 |
| 1990 | 51 |
| 1991 | 39 |
| 1992 | 39 |
| 1993 | 20 |
| 1994 | 16 |
| 1995 | 12 |
| 1996 | 7 |
| 1997 | 6 |
| 1998 | 6 |
| 1999 | 6 |
| 2000 | 6 |
| 2001 | 9 |
| 2002 | 8 |
| 2006 | 5 |
| 2009 | 5 |