| Year | Rank | Number |
| 2011 | 9848 | 7 |
| 2010 | 6774 | 12 |
| 2009 | 5834 | 15 |
| 2008 | 4574 | 21 |
| 2007 | 8349 | 9 |
| 2006 | 6193 | 13 |
| 2005 | 6749 | 11 |
| 2004 | 7699 | 9 |
| 2003 | 6369 | 11 |
| 2002 | 7848 | 8 |
| 2001 | 9603 | 6 |
| 2000 | 7638 | 8 |
| 1999 | 6162 | 10 |
| 1998 | 7812 | 7 |
| 1997 | 9694 | 5 |
| 1990 | 8486 | 5 |
| 1986 | 6156 | 6 |
| 1985 | 6001 | 6 |
| 1980 | 6524 | 5 |
| 1977 | 4733 | 7 |
| 1976 | 5094 | 6 |
| 1972 | 3724 | 8 |