| Year | Count |
|---|---|
| 1971 | 55 |
| 1972 | 16 |
| 1974 | 7 |
| 1975 | 12 |
| 1976 | 6 |
| 1977 | 11 |
| 1978 | 7 |
| 1979 | 16 |
| 1980 | 44 |
| 1981 | 12 |
| 1982 | 83 |
| 1983 | 148 |
| 1984 | 170 |
| 1985 | 344 |
| 1986 | 346 |
| 1987 | 351 |
| 1988 | 364 |
| 1989 | 425 |
| 1990 | 292 |
| 1991 | 327 |
| 1992 | 196 |
| 1993 | 179 |
| 1994 | 160 |
| 1995 | 205 |
| 1996 | 246 |
| 1997 | 160 |
| 1998 | 107 |
| 1999 | 80 |
| 2000 | 63 |
| 2001 | 46 |
| 2002 | 23 |
| 2003 | 18 |
| 2004 | 47 |
| 2005 | 46 |
| 2006 | 28 |
| 2007 | 7 |
| 2008 | 20 |
| 2009 | 10 |