| Year | Count |
|---|---|
| 1969 | 9 |
| 1974 | 7 |
| 1976 | 5 |
| 1979 | 5 |
| 1980 | 7 |
| 1981 | 6 |
| 1982 | 10 |
| 1983 | 15 |
| 1984 | 18 |
| 1985 | 22 |
| 1986 | 17 |
| 1987 | 15 |
| 1988 | 16 |
| 1989 | 15 |
| 1991 | 12 |
| 1992 | 7 |
| 1993 | 8 |
| 1994 | 5 |
| 1995 | 6 |
| 1996 | 5 |
| 1997 | 7 |
| 1998 | 13 |
| 1999 | 13 |
| 2000 | 8 |
| 2001 | 14 |
| 2002 | 15 |
| 2003 | 17 |
| 2004 | 24 |
| 2005 | 25 |
| 2006 | 32 |
| 2007 | 38 |
| 2008 | 38 |
| 2009 | 48 |
| 2010 | 79 |
| 2011 | 79 |
| 2012 | 87 |
| 2013 | 92 |
| 2014 | 119 |
| 2015 | 135 |
| 2016 | 252 |
| 2017 | 338 |
| 2018 | 342 |
| 2019 | 408 |
| 2020 | 198 |
| 2021 | 177 |
| 2022 | 165 |
| 2023 | 159 |
| 2024 | 140 |