| Year | Rank | Number |
| 2011 | 6262 | 21 |
| 2010 | 8576 | 14 |
| 2009 | 12140 | 9 |
| 2008 | 11377 | 10 |
| 2007 | 8410 | 15 |
| 2006 | 13304 | 8 |
| 2005 | 8742 | 13 |
| 2004 | 8607 | 13 |
| 2003 | 7896 | 14 |
| 2002 | 8698 | 12 |
| 2001 | 13153 | 7 |
| 1999 | 10136 | 9 |
| 1995 | 12985 | 6 |
| 1991 | 14824 | 5 |
| 1990 | 11070 | 7 |
| 1989 | 10548 | 7 |
| 1988 | 10082 | 7 |
| 1987 | 12721 | 5 |
| 1974 | 9809 | 5 |