| Year | Rank | Number |
| 2011 | 17611 | 5 |
| 2010 | 8862 | 13 |
| 2007 | 13063 | 8 |
| 2006 | 18084 | 5 |
| 2005 | 17370 | 5 |
| 2004 | 14776 | 6 |
| 2003 | 11685 | 8 |
| 2002 | 14198 | 6 |
| 2001 | 14128 | 6 |
| 2000 | 13754 | 6 |
| 1998 | 11555 | 7 |
| 1997 | 10131 | 8 |
| 1996 | 6493 | 14 |
| 1995 | 6370 | 14 |
| 1994 | 7783 | 11 |
| 1993 | 12309 | 6 |
| 1991 | 8839 | 9 |
| 1990 | 13740 | 5 |
| 1989 | 13074 | 5 |
| 1980 | 10915 | 5 |