| Year | Count |
|---|---|
| 1971 | 7 |
| 1972 | 10 |
| 1974 | 5 |
| 1976 | 6 |
| 1977 | 8 |
| 1979 | 6 |
| 1985 | 6 |
| 1991 | 5 |
| 1992 | 6 |
| 1994 | 5 |
| 1995 | 6 |
| 1996 | 7 |
| 1997 | 10 |
| 1998 | 7 |
| 1999 | 10 |
| 2000 | 12 |
| 2001 | 9 |
| 2002 | 9 |
| 2003 | 12 |
| 2005 | 15 |
| 2006 | 13 |
| 2007 | 7 |
| 2008 | 6 |
| 2009 | 8 |
| 2010 | 7 |
| 2011 | 15 |
| 2012 | 12 |
| 2013 | 7 |
| 2014 | 9 |
| 2015 | 14 |
| 2016 | 12 |
| 2017 | 14 |
| 2018 | 12 |
| 2021 | 6 |
| 2022 | 9 |
| 2023 | 8 |
| 2024 | 7 |