| Year | Rank | Number |
| 2011 | 7176 | 17 |
| 2010 | 9392 | 12 |
| 2009 | 8119 | 15 |
| 2008 | 9664 | 12 |
| 2007 | 7833 | 16 |
| 2006 | 8400 | 14 |
| 2005 | 5488 | 23 |
| 2004 | 6312 | 19 |
| 2003 | 6147 | 19 |
| 2002 | 7558 | 14 |
| 2001 | 4131 | 30 |
| 2000 | 6924 | 15 |
| 1999 | 4921 | 22 |
| 1998 | 7719 | 12 |
| 1997 | 10140 | 8 |
| 1996 | 6495 | 14 |
| 1995 | 12324 | 6 |
| 1994 | 10970 | 7 |
| 1993 | 7183 | 12 |
| 1991 | 12036 | 6 |
| 1990 | 13765 | 5 |
| 1989 | 10082 | 7 |
| 1988 | 10825 | 6 |
| 1987 | 8256 | 8 |