| Year | Count |
|---|---|
| 1969 | 9 |
| 1970 | 7 |
| 1971 | 21 |
| 1972 | 31 |
| 1973 | 43 |
| 1974 | 61 |
| 1975 | 81 |
| 1976 | 118 |
| 1977 | 366 |
| 1978 | 346 |
| 1979 | 468 |
| 1979 | 7 |
| 1980 | 438 |
| 1981 | 219 |
| 1982 | 280 |
| 1983 | 280 |
| 1984 | 232 |
| 1985 | 249 |
| 1986 | 168 |
| 1987 | 167 |
| 1988 | 170 |
| 1989 | 152 |
| 1990 | 133 |
| 1991 | 142 |
| 1992 | 112 |
| 1993 | 98 |
| 1994 | 90 |
| 1995 | 80 |
| 1996 | 56 |
| 1997 | 54 |
| 1998 | 41 |
| 1999 | 46 |
| 2000 | 29 |
| 2001 | 35 |
| 2002 | 22 |
| 2003 | 14 |
| 2004 | 19 |
| 2005 | 19 |
| 2006 | 13 |
| 2007 | 12 |
| 2008 | 8 |
| 2012 | 6 |
| 2016 | 15 |