| Year | Rank | Number |
| 2011 | 7851 | 15 |
| 2010 | 6691 | 19 |
| 2009 | 7343 | 17 |
| 2008 | 7801 | 16 |
| 2007 | 5389 | 26 |
| 2006 | 4976 | 28 |
| 2005 | 7985 | 14 |
| 2004 | 6840 | 17 |
| 2003 | 7289 | 15 |
| 2002 | 5487 | 21 |
| 2001 | 6686 | 16 |
| 2000 | 8680 | 11 |
| 1999 | 6571 | 15 |
| 1998 | 5859 | 17 |
| 1997 | 11118 | 7 |
| 1996 | 6136 | 15 |
| 1995 | 6331 | 14 |
| 1994 | 7714 | 11 |
| 1993 | 12114 | 6 |
| 1992 | 12100 | 6 |
| 1991 | 13635 | 5 |
| 1990 | 10459 | 7 |
| 1989 | 8924 | 8 |
| 1987 | 8977 | 7 |
| 1983 | 9281 | 6 |
| 1978 | 10074 | 5 |