| Year | Total | vs prev |
|---|---|---|
| 2011 | 0 | −100.0% |
| 2010 | 3 | −99.6% |
| 2009 | 674 | −6.8% |
| 2008 | 723 | −41.1% |
| 2007 | 1,228 | −15.8% |
| 2006 | 1,459 | −15.0% |
| 2005 | 1,717 | −12.1% |
| 2004 | 1,954 | +0.1% |
| 2003 | 1,952 | +152.2% |
| 2002 | 774 | −14.4% |
| 2001 | 904 | −15.4% |
| 2000 | 1,068 | +13.9% |
| 1999 | 938 | +82.8% |
| 1998 | 513 | +291.6% |
| 1997 | 131 | — |