| Year | Count |
|---|---|
| 1975 | 5 |
| 1976 | 16 |
| 1977 | 52 |
| 1978 | 136 |
| 1979 | 208 |
| 1980 | 229 |
| 1981 | 433 |
| 1982 | 715 |
| 1983 | 757 |
| 1984 | 764 |
| 1985 | 815 |
| 1986 | 861 |
| 1987 | 791 |
| 1988 | 794 |
| 1989 | 694 |
| 1990 | 736 |
| 1991 | 799 |
| 1992 | 551 |
| 1993 | 523 |
| 1994 | 575 |
| 1995 | 393 |
| 1996 | 390 |
| 1997 | 513 |
| 1998 | 415 |
| 1999 | 320 |
| 2000 | 357 |
| 2001 | 353 |
| 2002 | 186 |
| 2003 | 227 |
| 2004 | 272 |
| 2005 | 279 |
| 2006 | 230 |
| 2007 | 127 |
| 2008 | 164 |
| 2009 | 83 |
| 2010 | 62 |
| 2011 | 27 |
| 2012 | 15 |
| 2013 | 25 |
| 2014 | 10 |
| 2015 | 7 |
| 2016 | 5 |
| 2017 | 6 |
| 2018 | 7 |
| 2022 | 10 |
| 2023 | 5 |