| Year | Count |
|---|---|
| 1971 | 6 |
| 1973 | 5 |
| 1974 | 5 |
| 1977 | 5 |
| 1979 | 5 |
| 1980 | 7 |
| 1981 | 13 |
| 1983 | 6 |
| 1984 | 14 |
| 1985 | 33 |
| 1986 | 22 |
| 1987 | 10 |
| 1988 | 17 |
| 1991 | 15 |
| 1992 | 21 |
| 1993 | 19 |
| 1994 | 21 |
| 1995 | 18 |
| 1996 | 56 |
| 1997 | 35 |
| 1998 | 49 |
| 1999 | 18 |
| 2000 | 25 |
| 2001 | 79 |
| 2002 | 50 |
| 2003 | 38 |
| 2004 | 144 |
| 2005 | 148 |
| 2006 | 106 |
| 2007 | 81 |
| 2008 | 81 |
| 2009 | 27 |
| 2010 | 14 |
| 2011 | 34 |
| 2012 | 38 |
| 2013 | 6 |
| 2014 | 19 |
| 2015 | 35 |
| 2016 | 29 |
| 2017 | 21 |
| 2018 | 9 |
| 2019 | 16 |
| 2020 | 16 |
| 2021 | 27 |
| 2022 | 20 |
| 2023 | 17 |
| 2024 | 14 |