| Year | Rank | Number |
| 2011 | 18254 | 5 |
| 2010 | 18568 | 5 |
| 2007 | 19202 | 5 |
| 2005 | 17994 | 5 |
| 2004 | 10345 | 10 |
| 2003 | 10094 | 10 |
| 2002 | 16977 | 5 |
| 2000 | 12547 | 7 |
| 1999 | 13635 | 6 |
| 1997 | 11515 | 7 |
| 1995 | 9188 | 9 |
| 1993 | 14735 | 5 |
| 1992 | 9163 | 9 |
| 1991 | 14398 | 5 |
| 1989 | 11660 | 6 |
| 1987 | 6161 | 12 |
| 1986 | 9086 | 7 |
| 1982 | 11438 | 5 |
| 1981 | 11303 | 5 |