| Year | Count |
|---|---|
| 1960 | 7 |
| 1961 | 5 |
| 1962 | 5 |
| 1965 | 5 |
| 1967 | 6 |
| 1969 | 6 |
| 1970 | 6 |
| 1973 | 6 |
| 1975 | 7 |
| 1980 | 6 |
| 1981 | 6 |
| 1983 | 8 |
| 1984 | 8 |
| 1985 | 9 |
| 1986 | 6 |
| 1987 | 9 |
| 1988 | 9 |
| 1989 | 6 |
| 1990 | 9 |
| 1991 | 6 |
| 1992 | 10 |
| 1993 | 9 |
| 1994 | 8 |
| 1995 | 5 |
| 1996 | 13 |
| 1997 | 5 |
| 1998 | 9 |
| 1999 | 7 |
| 2000 | 7 |
| 2001 | 13 |
| 2002 | 9 |
| 2003 | 7 |
| 2004 | 13 |
| 2005 | 18 |
| 2006 | 18 |
| 2007 | 19 |
| 2008 | 13 |
| 2009 | 19 |
| 2010 | 12 |
| 2011 | 10 |
| 2012 | 18 |
| 2013 | 16 |
| 2014 | 6 |
| 2015 | 16 |
| 2016 | 34 |
| 2017 | 40 |
| 2018 | 46 |
| 2019 | 30 |
| 2020 | 22 |
| 2021 | 30 |
| 2022 | 30 |
| 2023 | 36 |
| 2024 | 21 |