| Year | Count |
|---|---|
| 1968 | 5 |
| 1969 | 38 |
| 1970 | 32 |
| 1971 | 11 |
| 1972 | 10 |
| 1973 | 18 |
| 1974 | 11 |
| 1975 | 24 |
| 1976 | 23 |
| 1977 | 75 |
| 1978 | 49 |
| 1979 | 60 |
| 1980 | 62 |
| 1981 | 58 |
| 1982 | 37 |
| 1983 | 37 |
| 1984 | 10 |
| 1985 | 29 |
| 1986 | 68 |
| 1987 | 96 |
| 1988 | 24 |
| 1989 | 55 |
| 1990 | 113 |
| 1991 | 53 |
| 1992 | 58 |
| 1993 | 70 |
| 1994 | 26 |
| 1995 | 26 |
| 1996 | 22 |
| 1997 | 27 |
| 1999 | 21 |
| 2000 | 5 |
| 2001 | 16 |
| 2015 | 5 |