| Year | Rank | Number |
| 2011 | 7517 | 16 |
| 2010 | 3972 | 38 |
| 2009 | 4573 | 32 |
| 2008 | 3721 | 43 |
| 2007 | 3799 | 42 |
| 2006 | 3806 | 40 |
| 2005 | 5143 | 25 |
| 2004 | 5256 | 24 |
| 2003 | 5467 | 22 |
| 2002 | 4672 | 26 |
| 2001 | 5657 | 20 |
| 2000 | 8205 | 12 |
| 1999 | 6012 | 17 |
| 1998 | 7718 | 12 |
| 1997 | 11251 | 7 |
| 1996 | 12380 | 6 |
| 1995 | 9895 | 8 |
| 1994 | 12327 | 6 |
| 1993 | 9899 | 8 |
| 1990 | 13764 | 5 |
| 1989 | 9025 | 8 |
| 1988 | 9602 | 7 |