| Year | Count |
|---|---|
| 1971 | 38 |
| 1972 | 55 |
| 1973 | 69 |
| 1974 | 80 |
| 1975 | 115 |
| 1976 | 171 |
| 1977 | 194 |
| 1978 | 209 |
| 1979 | 301 |
| 1980 | 381 |
| 1981 | 365 |
| 1982 | 389 |
| 1983 | 365 |
| 1984 | 267 |
| 1985 | 307 |
| 1986 | 230 |
| 1987 | 249 |
| 1988 | 220 |
| 1989 | 257 |
| 1990 | 210 |
| 1991 | 200 |
| 1992 | 160 |
| 1993 | 223 |
| 1994 | 136 |
| 1995 | 134 |
| 1996 | 161 |
| 1997 | 786 |
| 1998 | 1,137 |
| 1999 | 841 |
| 2000 | 632 |
| 2001 | 759 |
| 2002 | 351 |
| 2003 | 216 |
| 2004 | 123 |
| 2005 | 95 |
| 2006 | 69 |
| 2007 | 56 |
| 2008 | 41 |
| 2009 | 34 |
| 2010 | 24 |
| 2011 | 24 |
| 2012 | 16 |
| 2013 | 10 |
| 2014 | 12 |
| 2015 | 14 |
| 2020 | 12 |