| Year | Count |
|---|---|
| 1970 | 10 |
| 1972 | 17 |
| 1973 | 21 |
| 1974 | 37 |
| 1975 | 56 |
| 1976 | 98 |
| 1977 | 107 |
| 1978 | 168 |
| 1979 | 214 |
| 1980 | 220 |
| 1981 | 207 |
| 1982 | 293 |
| 1983 | 242 |
| 1984 | 245 |
| 1985 | 295 |
| 1986 | 304 |
| 1987 | 309 |
| 1988 | 273 |
| 1989 | 272 |
| 1990 | 280 |
| 1991 | 309 |
| 1992 | 300 |
| 1993 | 267 |
| 1994 | 252 |
| 1995 | 259 |
| 1996 | 210 |
| 1997 | 168 |
| 1998 | 196 |
| 1999 | 153 |
| 2000 | 91 |
| 2001 | 55 |
| 2002 | 59 |
| 2003 | 44 |
| 2004 | 40 |
| 2005 | 66 |
| 2006 | 34 |
| 2007 | 40 |
| 2008 | 45 |
| 2010 | 6 |