| Year | Total | vs prev |
|---|---|---|
| 2010 | 0 | −100.0% |
| 2009 | 13 | −88.6% |
| 2008 | 114 | −93.3% |
| 2007 | 1,703 | +54.1% |
| 2006 | 1,105 | −39.6% |
| 2005 | 1,829 | −9.3% |
| 2004 | 2,016 | −15.6% |
| 2003 | 2,389 | +19.4% |
| 2002 | 2,001 | −13.2% |
| 2001 | 2,306 | −17.0% |
| 2000 | 2,779 | −38.1% |
| 1999 | 4,487 | +44.9% |
| 1998 | 3,097 | −24.5% |
| 1997 | 4,100 | −1.1% |
| 1996 | 4,145 | −19.4% |
| 1995 | 5,144 | +59.8% |
| 1994 | 3,219 | −23.5% |
| 1993 | 4,206 | −2.4% |
| 1992 | 4,308 | +14.5% |
| 1991 | 3,762 | — |