| Year | Rank | Number |
| 2011 | 18231 | 5 |
| 2010 | 10828 | 10 |
| 2009 | 9641 | 12 |
| 2008 | 10435 | 11 |
| 2007 | 10492 | 11 |
| 2006 | 14395 | 7 |
| 2005 | 11405 | 9 |
| 2004 | 15188 | 6 |
| 2003 | 14903 | 6 |
| 2002 | 9914 | 10 |
| 2001 | 12815 | 7 |
| 2000 | 12533 | 7 |
| 1999 | 10923 | 8 |
| 1998 | 15442 | 5 |
| 1996 | 14765 | 5 |
| 1995 | 12628 | 6 |
| 1993 | 11222 | 7 |
| 1991 | 12345 | 6 |
| 1990 | 10837 | 7 |
| 1988 | 6885 | 11 |
| 1986 | 11884 | 5 |
| 1985 | 11588 | 5 |
| 1981 | 11259 | 5 |