| Year | Count |
|---|---|
| 1970 | 6 |
| 1971 | 6 |
| 1974 | 7 |
| 1975 | 5 |
| 1976 | 12 |
| 1978 | 12 |
| 1979 | 12 |
| 1982 | 8 |
| 1983 | 7 |
| 1984 | 9 |
| 1985 | 9 |
| 1986 | 17 |
| 1987 | 10 |
| 1988 | 10 |
| 1989 | 12 |
| 1990 | 18 |
| 1991 | 6 |
| 1992 | 15 |
| 1993 | 15 |
| 1994 | 13 |
| 1995 | 13 |
| 1996 | 7 |
| 1997 | 28 |
| 1998 | 31 |
| 1999 | 27 |
| 2000 | 27 |
| 2001 | 22 |
| 2002 | 30 |
| 2003 | 33 |
| 2004 | 32 |
| 2005 | 28 |
| 2006 | 29 |
| 2007 | 34 |
| 2008 | 47 |
| 2009 | 29 |
| 2010 | 39 |
| 2011 | 54 |
| 2012 | 52 |
| 2013 | 61 |
| 2014 | 78 |
| 2015 | 60 |
| 2016 | 216 |
| 2017 | 213 |
| 2018 | 60 |
| 2019 | 116 |
| 2020 | 208 |
| 2021 | 150 |
| 2022 | 168 |
| 2023 | 182 |
| 2024 | 204 |