| Year | Count |
|---|---|
| 1968 | 5 |
| 1976 | 5 |
| 1978 | 16 |
| 1979 | 8 |
| 1980 | 5 |
| 1983 | 9 |
| 1985 | 5 |
| 1987 | 5 |
| 1988 | 6 |
| 1989 | 5 |
| 1991 | 7 |
| 1992 | 6 |
| 1993 | 8 |
| 1994 | 5 |
| 1995 | 7 |
| 1997 | 9 |
| 1999 | 8 |
| 2000 | 5 |
| 2001 | 5 |
| 2002 | 6 |
| 2003 | 6 |
| 2004 | 5 |
| 2005 | 5 |
| 2006 | 6 |
| 2008 | 6 |
| 2009 | 6 |
| 2011 | 8 |
| 2012 | 6 |
| 2013 | 7 |
| 2014 | 5 |
| 2015 | 12 |
| 2016 | 20 |
| 2017 | 18 |
| 2018 | 18 |
| 2019 | 8 |
| 2021 | 6 |
| 2022 | 5 |
| 2023 | 6 |
| 2024 | 7 |