| Year | Count |
|---|---|
| 1978 | 14 |
| 1979 | 19 |
| 1980 | 6 |
| 1981 | 6 |
| 1983 | 7 |
| 1984 | 7 |
| 1988 | 6 |
| 1995 | 6 |
| 1996 | 6 |
| 1997 | 10 |
| 1998 | 95 |
| 1999 | 111 |
| 2000 | 56 |
| 2001 | 47 |
| 2002 | 32 |
| 2003 | 42 |
| 2004 | 48 |
| 2005 | 115 |
| 2006 | 72 |
| 2007 | 142 |
| 2008 | 51 |
| 2009 | 26 |
| 2010 | 34 |
| 2011 | 28 |
| 2012 | 11 |
| 2013 | 5 |
| 2015 | 8 |
| 2016 | 10 |
| 2017 | 15 |
| 2018 | 12 |
| 2019 | 16 |
| 2021 | 5 |