| Year | Count |
|---|---|
| 1957 | 16 |
| 1958 | 20 |
| 1959 | 30 |
| 1960 | 50 |
| 1961 | 68 |
| 1963 | 37 |
| 1964 | 45 |
| 1965 | 69 |
| 1966 | 61 |
| 1967 | 73 |
| 1968 | 94 |
| 1969 | 149 |
| 1970 | 163 |
| 1971 | 91 |
| 1972 | 77 |
| 1973 | 60 |
| 1974 | 42 |
| 1975 | 51 |
| 1976 | 50 |
| 1977 | 156 |
| 1978 | 138 |
| 1979 | 108 |
| 1980 | 164 |
| 1981 | 62 |
| 1982 | 69 |
| 1983 | 51 |
| 1984 | 40 |
| 1985 | 52 |
| 1986 | 48 |
| 1987 | 66 |
| 1988 | 53 |
| 1989 | 50 |
| 1990 | 47 |
| 1991 | 46 |
| 1992 | 37 |
| 1993 | 33 |
| 1994 | 34 |
| 1995 | 27 |
| 1996 | 26 |
| 1997 | 19 |
| 1998 | 15 |
| 1999 | 23 |
| 2000 | 16 |
| 2001 | 12 |
| 2002 | 19 |
| 2003 | 16 |
| 2004 | 7 |
| 2007 | 5 |
| 2010 | 5 |