| Year | Count |
|---|---|
| 1988 | 10 |
| 1989 | 8 |
| 1990 | 11 |
| 1991 | 14 |
| 1992 | 5 |
| 1993 | 10 |
| 1994 | 5 |
| 1995 | 5 |
| 1996 | 16 |
| 1997 | 10 |
| 1999 | 31 |
| 2000 | 25 |
| 2001 | 20 |
| 2002 | 23 |
| 2003 | 72 |
| 2004 | 56 |
| 2005 | 85 |
| 2006 | 46 |
| 2007 | 42 |
| 2008 | 50 |
| 2009 | 29 |
| 2010 | 76 |
| 2011 | 67 |
| 2012 | 39 |
| 2013 | 17 |
| 2014 | 38 |
| 2015 | 37 |
| 2016 | 16 |
| 2017 | 36 |
| 2018 | 10 |
| 2019 | 20 |
| 2020 | 10 |
| 2021 | 5 |