| Year | Count |
|---|---|
| 1967 | 6 |
| 1968 | 6 |
| 1969 | 6 |
| 1970 | 12 |
| 1972 | 5 |
| 1975 | 5 |
| 1977 | 10 |
| 1978 | 5 |
| 1980 | 12 |
| 1981 | 25 |
| 1982 | 146 |
| 1983 | 100 |
| 1984 | 82 |
| 1985 | 127 |
| 1986 | 157 |
| 1987 | 125 |
| 1988 | 135 |
| 1989 | 315 |
| 1990 | 306 |
| 1991 | 298 |
| 1992 | 190 |
| 1993 | 149 |
| 1994 | 97 |
| 1995 | 63 |
| 1996 | 75 |
| 1997 | 37 |
| 1998 | 23 |
| 1999 | 19 |
| 2000 | 7 |
| 2001 | 12 |
| 2003 | 7 |
| 2004 | 10 |
| 2005 | 10 |