| Year | Count |
|---|---|
| 1968 | 48 |
| 1969 | 56 |
| 1970 | 72 |
| 1971 | 77 |
| 1972 | 94 |
| 1973 | 72 |
| 1974 | 50 |
| 1975 | 96 |
| 1976 | 123 |
| 1977 | 121 |
| 1978 | 54 |
| 1979 | 129 |
| 1980 | 103 |
| 1981 | 114 |
| 1982 | 134 |
| 1983 | 152 |
| 1984 | 118 |
| 1985 | 179 |
| 1986 | 203 |
| 1987 | 234 |
| 1988 | 209 |
| 1989 | 306 |
| 1989 | 6 |
| 1990 | 277 |
| 1991 | 219 |
| 1992 | 198 |
| 1993 | 188 |
| 1994 | 150 |
| 1995 | 136 |
| 1996 | 116 |
| 1997 | 66 |
| 1998 | 64 |
| 1999 | 59 |
| 2000 | 17 |
| 2001 | 12 |
| 2002 | 12 |
| 2003 | 5 |
| 2004 | 7 |
| 2008 | 10 |
| 2010 | 15 |
| 2015 | 6 |
| 2020 | 20 |
| 2024 | 5 |