| Year | Count |
|---|---|
| 1968 | 15 |
| 1969 | 17 |
| 1970 | 38 |
| 1971 | 50 |
| 1972 | 72 |
| 1973 | 98 |
| 1974 | 115 |
| 1975 | 144 |
| 1976 | 154 |
| 1977 | 145 |
| 1978 | 147 |
| 1979 | 175 |
| 1980 | 149 |
| 1981 | 142 |
| 1982 | 157 |
| 1983 | 153 |
| 1984 | 220 |
| 1985 | 99 |
| 1986 | 154 |
| 1987 | 200 |
| 1988 | 175 |
| 1989 | 171 |
| 1990 | 137 |
| 1991 | 164 |
| 1992 | 139 |
| 1993 | 135 |
| 1994 | 150 |
| 1995 | 65 |
| 1996 | 66 |
| 1997 | 62 |
| 1998 | 53 |
| 1999 | 33 |
| 2000 | 19 |
| 2001 | 12 |
| 2002 | 26 |
| 2003 | 19 |
| 2004 | 5 |
| 2006 | 18 |