| Year | Count |
|---|---|
| 1975 | 6 |
| 1976 | 7 |
| 1977 | 20 |
| 1978 | 33 |
| 1979 | 76 |
| 1980 | 50 |
| 1981 | 54 |
| 1982 | 64 |
| 1983 | 49 |
| 1984 | 91 |
| 1985 | 155 |
| 1986 | 180 |
| 1987 | 244 |
| 1988 | 170 |
| 1989 | 180 |
| 1990 | 146 |
| 1991 | 236 |
| 1992 | 190 |
| 1993 | 111 |
| 1994 | 69 |
| 1995 | 84 |
| 1996 | 44 |
| 1997 | 69 |
| 1998 | 64 |
| 1999 | 18 |
| 2001 | 11 |
| 2002 | 10 |
| 2004 | 5 |
| 2005 | 10 |
| 2007 | 19 |