| Year | Count |
|---|---|
| 1961 | 5 |
| 1963 | 6 |
| 1966 | 10 |
| 1967 | 5 |
| 1968 | 42 |
| 1969 | 29 |
| 1970 | 49 |
| 1971 | 104 |
| 1972 | 80 |
| 1973 | 55 |
| 1974 | 68 |
| 1975 | 42 |
| 1976 | 57 |
| 1977 | 45 |
| 1978 | 54 |
| 1979 | 59 |
| 1980 | 54 |
| 1981 | 33 |
| 1982 | 41 |
| 1983 | 23 |
| 1984 | 44 |
| 1985 | 105 |
| 1986 | 142 |
| 1987 | 57 |
| 1988 | 59 |
| 1989 | 53 |
| 1990 | 48 |
| 1991 | 43 |
| 1992 | 31 |
| 1993 | 48 |
| 1994 | 31 |
| 1995 | 26 |
| 1996 | 12 |
| 1997 | 21 |
| 2001 | 5 |
| 2003 | 12 |
| 2004 | 16 |
| 2005 | 16 |
| 2006 | 7 |
| 2007 | 9 |
| 2010 | 5 |
| 2015 | 6 |