| Year | Count |
|---|---|
| 1976 | 5 |
| 1979 | 5 |
| 1980 | 5 |
| 1983 | 5 |
| 1984 | 22 |
| 1985 | 30 |
| 1986 | 45 |
| 1987 | 69 |
| 1988 | 105 |
| 1989 | 199 |
| 1990 | 304 |
| 1991 | 517 |
| 1992 | 509 |
| 1993 | 664 |
| 1994 | 715 |
| 1995 | 599 |
| 1996 | 731 |
| 1997 | 629 |
| 1998 | 630 |
| 1999 | 485 |
| 2000 | 416 |
| 2001 | 355 |
| 2002 | 337 |
| 2003 | 343 |
| 2004 | 443 |
| 2005 | 359 |
| 2006 | 335 |
| 2007 | 343 |
| 2008 | 160 |
| 2009 | 114 |
| 2010 | 144 |
| 2011 | 56 |
| 2012 | 10 |