| Year | Rank | Number |
| 2011 | 17896 | 5 |
| 2010 | 18160 | 5 |
| 2009 | 14234 | 7 |
| 2008 | 14452 | 7 |
| 2007 | 16346 | 6 |
| 2006 | 12869 | 8 |
| 2005 | 12326 | 8 |
| 2004 | 10243 | 10 |
| 2003 | 13024 | 7 |
| 2002 | 7210 | 15 |
| 2001 | 9007 | 11 |
| 2000 | 12357 | 7 |
| 1999 | 8464 | 11 |
| 1998 | 8879 | 10 |
| 1997 | 8625 | 10 |
| 1996 | 6891 | 13 |
| 1995 | 7245 | 12 |
| 1994 | 7300 | 12 |
| 1993 | 5516 | 17 |
| 1992 | 9879 | 8 |
| 1991 | 8230 | 10 |
| 1990 | 7049 | 12 |
| 1989 | 11413 | 6 |
| 1988 | 7967 | 9 |
| 1987 | 9184 | 7 |
| 1985 | 11361 | 5 |
| 1981 | 7020 | 9 |
| 1979 | 10829 | 5 |
| 1978 | 7971 | 7 |