| Year | Rank | Number |
| 2011 | 12807 | 5 |
| 2010 | 9035 | 8 |
| 2009 | 6868 | 12 |
| 2008 | 11486 | 6 |
| 2007 | 6000 | 14 |
| 2006 | 8211 | 9 |
| 2005 | 6339 | 12 |
| 2004 | 6248 | 12 |
| 2003 | 8086 | 8 |
| 2002 | 6219 | 11 |
| 2001 | 7092 | 9 |
| 2000 | 7012 | 9 |
| 1999 | 5771 | 11 |
| 1998 | 7068 | 8 |
| 1997 | 6814 | 8 |
| 1996 | 7391 | 7 |
| 1995 | 6589 | 8 |
| 1994 | 9283 | 5 |
| 1993 | 4309 | 14 |
| 1992 | 7775 | 6 |
| 1991 | 5658 | 9 |
| 1989 | 5820 | 8 |
| 1988 | 5366 | 8 |
| 1982 | 4340 | 9 |
| 1981 | 5107 | 7 |
| 1980 | 5763 | 6 |
| 1979 | 5587 | 6 |
| 1978 | 6117 | 5 |
| 1977 | 6180 | 5 |