| Year | Total | vs prev |
|---|---|---|
| 2018 | 0 | −100.0% |
| 2017 | 1 | −50.0% |
| 2016 | 2 | −95.6% |
| 2015 | 45 | −41.6% |
| 2014 | 77 | −54.2% |
| 2013 | 168 | +9.8% |
| 2012 | 153 | −28.5% |
| 2011 | 214 | −30.5% |
| 2010 | 308 | −24.3% |
| 2009 | 407 | +24.1% |
| 2008 | 328 | −34.0% |
| 2007 | 497 | −9.5% |
| 2006 | 549 | −37.1% |
| 2005 | 873 | −8.8% |
| 2004 | 957 | −15.1% |
| 2003 | 1,127 | −6.5% |
| 2002 | 1,205 | +23.7% |
| 2001 | 974 | −8.3% |
| 2000 | 1,062 | −11.3% |
| 1999 | 1,197 | −6.3% |
| 1998 | 1,277 | −0.2% |
| 1997 | 1,279 | — |