| Year | Count |
|---|---|
| 1970 | 17 |
| 1971 | 113 |
| 1972 | 154 |
| 1973 | 141 |
| 1974 | 185 |
| 1975 | 164 |
| 1976 | 375 |
| 1977 | 288 |
| 1978 | 224 |
| 1979 | 229 |
| 1980 | 203 |
| 1981 | 102 |
| 1982 | 144 |
| 1983 | 95 |
| 1984 | 33 |
| 1985 | 92 |
| 1986 | 77 |
| 1987 | 33 |
| 1988 | 55 |
| 1989 | 49 |
| 1990 | 43 |
| 1991 | 62 |
| 1992 | 15 |
| 1993 | 34 |
| 1994 | 16 |
| 1995 | 15 |
| 1997 | 12 |
| 2003 | 5 |
| 2004 | 5 |
| 2007 | 6 |