| Year | Count |
|---|---|
| 1971 | 12 |
| 1972 | 10 |
| 1974 | 28 |
| 1975 | 29 |
| 1976 | 41 |
| 1977 | 30 |
| 1978 | 39 |
| 1979 | 105 |
| 1980 | 85 |
| 1981 | 77 |
| 1982 | 149 |
| 1983 | 110 |
| 1984 | 116 |
| 1985 | 100 |
| 1986 | 73 |
| 1987 | 90 |
| 1988 | 63 |
| 1989 | 83 |
| 1990 | 54 |
| 1991 | 20 |
| 1992 | 47 |
| 1993 | 44 |
| 1994 | 49 |
| 1995 | 16 |
| 1996 | 16 |
| 1997 | 11 |
| 1998 | 20 |
| 1999 | 5 |
| 2000 | 6 |
| 2006 | 5 |