| Year | Total | vs prev |
|---|---|---|
| 2012 | 0 | −100.0% |
| 2011 | 2 | −99.3% |
| 2010 | 284 | −51.4% |
| 2009 | 584 | −67.6% |
| 2008 | 1,804 | −15.8% |
| 2007 | 2,143 | +7.9% |
| 2006 | 1,986 | −29.9% |
| 2005 | 2,832 | −22.2% |
| 2004 | 3,640 | −16.6% |
| 2003 | 4,363 | +0.4% |
| 2002 | 4,347 | −12.6% |
| 2001 | 4,971 | −10.7% |
| 2000 | 5,566 | +31.8% |
| 1999 | 4,222 | +10.9% |
| 1998 | 3,806 | −1.3% |
| 1997 | 3,857 | −12.5% |
| 1996 | 4,409 | −1.2% |
| 1995 | 4,461 | +11.8% |
| 1994 | 3,991 | +195.6% |
| 1993 | 1,350 | −41.1% |
| 1992 | 2,291 | +24.9% |
| 1991 | 1,835 | — |