| Year | Rank | Number |
| 2011 | 6525 | 13 |
| 2010 | 7053 | 12 |
| 2009 | 7145 | 12 |
| 2008 | 4871 | 20 |
| 2007 | 5185 | 18 |
| 2006 | 5057 | 18 |
| 2005 | 5262 | 16 |
| 2004 | 6504 | 12 |
| 2003 | 5253 | 15 |
| 2002 | 4485 | 18 |
| 2001 | 3712 | 23 |
| 2000 | 3915 | 21 |
| 1999 | 3825 | 20 |
| 1998 | 4012 | 18 |
| 1997 | 3455 | 21 |
| 1996 | 5175 | 12 |
| 1995 | 4272 | 15 |
| 1994 | 4532 | 14 |
| 1993 | 4217 | 15 |
| 1992 | 4103 | 15 |
| 1991 | 4468 | 13 |
| 1990 | 3301 | 19 |
| 1989 | 5603 | 9 |
| 1988 | 3908 | 13 |
| 1987 | 3330 | 15 |
| 1982 | 6366 | 6 |
| 1981 | 7255 | 5 |
| 1980 | 6229 | 6 |