| Year | Count |
|---|---|
| 1972 | 10 |
| 1974 | 5 |
| 1975 | 11 |
| 1976 | 10 |
| 1977 | 16 |
| 1978 | 102 |
| 1979 | 66 |
| 1980 | 95 |
| 1981 | 84 |
| 1982 | 116 |
| 1983 | 134 |
| 1984 | 239 |
| 1985 | 223 |
| 1986 | 283 |
| 1987 | 244 |
| 1988 | 267 |
| 1989 | 231 |
| 1990 | 247 |
| 1991 | 215 |
| 1992 | 166 |
| 1993 | 95 |
| 1994 | 101 |
| 1995 | 59 |
| 1996 | 26 |
| 1997 | 17 |
| 1998 | 16 |
| 1999 | 5 |
| 2004 | 14 |
| 2007 | 8 |
| 2008 | 7 |