| Year | Count |
|---|---|
| 1970 | 7 |
| 1971 | 11 |
| 1972 | 6 |
| 1973 | 10 |
| 1974 | 7 |
| 1975 | 9 |
| 1976 | 11 |
| 1977 | 17 |
| 1978 | 48 |
| 1979 | 36 |
| 1980 | 37 |
| 1981 | 33 |
| 1982 | 52 |
| 1983 | 34 |
| 1984 | 23 |
| 1985 | 53 |
| 1986 | 37 |
| 1987 | 25 |
| 1988 | 30 |
| 1989 | 65 |
| 1990 | 69 |
| 1991 | 43 |
| 1992 | 49 |
| 1993 | 68 |
| 1994 | 49 |
| 1995 | 46 |
| 1996 | 21 |
| 1997 | 68 |
| 1998 | 68 |
| 1999 | 87 |
| 2000 | 74 |
| 2001 | 20 |
| 2002 | 11 |
| 2003 | 10 |
| 2006 | 8 |
| 2010 | 10 |