| Year | Count |
|---|---|
| 1974 | 5 |
| 1978 | 12 |
| 1980 | 5 |
| 1981 | 6 |
| 1982 | 6 |
| 1984 | 10 |
| 1986 | 11 |
| 1987 | 5 |
| 1989 | 5 |
| 1991 | 7 |
| 1992 | 8 |
| 1995 | 5 |
| 1996 | 7 |
| 1997 | 5 |
| 1999 | 10 |
| 2001 | 5 |
| 2003 | 7 |
| 2004 | 12 |
| 2005 | 5 |
| 2006 | 5 |
| 2007 | 5 |
| 2008 | 6 |
| 2009 | 8 |
| 2010 | 9 |
| 2011 | 11 |
| 2012 | 11 |
| 2013 | 10 |
| 2014 | 15 |
| 2015 | 39 |
| 2016 | 39 |
| 2017 | 51 |
| 2019 | 26 |
| 2020 | 24 |