| Year | Count |
|---|---|
| 1968 | 7 |
| 1970 | 16 |
| 1971 | 8 |
| 1972 | 39 |
| 1973 | 26 |
| 1974 | 27 |
| 1975 | 32 |
| 1976 | 76 |
| 1977 | 211 |
| 1978 | 253 |
| 1979 | 203 |
| 1980 | 186 |
| 1981 | 203 |
| 1982 | 162 |
| 1983 | 145 |
| 1984 | 184 |
| 1985 | 419 |
| 1986 | 333 |
| 1987 | 308 |
| 1988 | 330 |
| 1989 | 366 |
| 1990 | 392 |
| 1991 | 260 |
| 1992 | 211 |
| 1993 | 291 |
| 1994 | 166 |
| 1995 | 129 |
| 1996 | 81 |
| 1997 | 45 |
| 1998 | 6 |
| 1999 | 20 |
| 2000 | 18 |
| 2001 | 6 |
| 2003 | 8 |
| 2008 | 12 |