| Year | Total | vs prev |
|---|---|---|
| 2007 | 0 | −100.0% |
| 2006 | 17 | −89.9% |
| 2005 | 168 | −45.5% |
| 2004 | 308 | −30.8% |
| 2003 | 445 | −25.6% |
| 2002 | 598 | −48.0% |
| 2001 | 1,151 | −47.7% |
| 2000 | 2,199 | +19.4% |
| 1999 | 1,842 | +1.0% |
| 1998 | 1,824 | −8.7% |
| 1997 | 1,997 | +0.7% |
| 1996 | 1,983 | −1.4% |
| 1995 | 2,012 | +4.4% |
| 1994 | 1,927 | +20.7% |
| 1993 | 1,597 | −33.9% |
| 1992 | 2,415 | −19.3% |
| 1991 | 2,994 | — |