| Year | Rank | Number |
| 2011 | 5384 | 25 |
| 2010 | 4755 | 30 |
| 2009 | 4567 | 32 |
| 2008 | 3124 | 54 |
| 2007 | 4226 | 36 |
| 2006 | 4016 | 37 |
| 2005 | 3597 | 41 |
| 2004 | 4116 | 34 |
| 2003 | 3428 | 42 |
| 2002 | 3161 | 45 |
| 2001 | 3967 | 32 |
| 2000 | 3678 | 35 |
| 1999 | 4485 | 25 |
| 1998 | 3952 | 29 |
| 1997 | 4555 | 23 |
| 1996 | 3656 | 30 |
| 1995 | 3807 | 28 |
| 1994 | 3049 | 38 |
| 1993 | 3811 | 28 |
| 1992 | 4911 | 20 |
| 1991 | 4240 | 24 |
| 1990 | 3451 | 31 |
| 1989 | 6653 | 12 |
| 1988 | 9551 | 7 |