| Year | Count |
|---|---|
| 1966 | 5 |
| 1967 | 8 |
| 1969 | 14 |
| 1970 | 20 |
| 1971 | 11 |
| 1972 | 20 |
| 1973 | 14 |
| 1974 | 17 |
| 1975 | 11 |
| 1976 | 27 |
| 1977 | 102 |
| 1978 | 140 |
| 1979 | 108 |
| 1980 | 132 |
| 1981 | 54 |
| 1982 | 54 |
| 1983 | 52 |
| 1984 | 57 |
| 1985 | 55 |
| 1986 | 40 |
| 1987 | 43 |
| 1988 | 33 |
| 1989 | 44 |
| 1990 | 42 |
| 1991 | 38 |
| 1992 | 31 |
| 1993 | 28 |
| 1994 | 27 |
| 1995 | 20 |
| 1996 | 12 |
| 1997 | 14 |
| 1998 | 8 |
| 1999 | 10 |
| 2000 | 6 |
| 2001 | 10 |
| 2002 | 8 |
| 2003 | 7 |
| 2004 | 5 |
| 2005 | 7 |
| 2006 | 10 |