| Year | Rank | Number |
| 2010 | 17828 | 5 |
| 2007 | 11074 | 10 |
| 2006 | 9469 | 12 |
| 2005 | 12183 | 8 |
| 2004 | 11972 | 8 |
| 2001 | 10371 | 9 |
| 2000 | 12206 | 7 |
| 1999 | 13226 | 6 |
| 1998 | 8173 | 11 |
| 1997 | 11218 | 7 |
| 1995 | 9873 | 8 |
| 1994 | 12285 | 6 |
| 1991 | 8164 | 10 |
| 1990 | 9549 | 8 |
| 1989 | 11282 | 6 |
| 1988 | 9567 | 7 |
| 1987 | 8239 | 8 |
| 1983 | 8302 | 7 |
| 1976 | 9750 | 5 |
| 1970 | 8382 | 5 |
| 1963 | 6091 | 6 |