| Year | Count |
|---|---|
| 1970 | 5 |
| 1976 | 5 |
| 1980 | 5 |
| 1984 | 7 |
| 1986 | 7 |
| 1989 | 6 |
| 1991 | 5 |
| 1992 | 5 |
| 1993 | 6 |
| 1994 | 6 |
| 1995 | 8 |
| 1996 | 15 |
| 1997 | 7 |
| 1998 | 11 |
| 1999 | 8 |
| 2000 | 11 |
| 2001 | 12 |
| 2002 | 5 |
| 2003 | 12 |
| 2004 | 6 |
| 2005 | 8 |
| 2006 | 10 |
| 2007 | 8 |
| 2008 | 11 |
| 2009 | 14 |
| 2010 | 13 |
| 2011 | 25 |
| 2012 | 15 |
| 2013 | 14 |
| 2014 | 7 |
| 2015 | 14 |
| 2016 | 34 |
| 2017 | 32 |
| 2018 | 50 |
| 2019 | 38 |
| 2020 | 17 |
| 2021 | 13 |
| 2022 | 18 |
| 2023 | 22 |
| 2024 | 17 |