| Year | Count |
|---|---|
| 1970 | 7 |
| 1975 | 5 |
| 1976 | 8 |
| 1977 | 22 |
| 1979 | 28 |
| 1980 | 28 |
| 1981 | 14 |
| 1982 | 15 |
| 1983 | 11 |
| 1984 | 14 |
| 1985 | 12 |
| 1986 | 12 |
| 1987 | 16 |
| 1988 | 33 |
| 1989 | 16 |
| 1990 | 22 |
| 1991 | 24 |
| 1992 | 36 |
| 1993 | 35 |
| 1994 | 26 |
| 1995 | 28 |
| 1996 | 54 |
| 1997 | 44 |
| 1998 | 53 |
| 1999 | 59 |
| 2000 | 57 |
| 2001 | 57 |
| 2002 | 84 |
| 2003 | 100 |
| 2004 | 119 |
| 2005 | 91 |
| 2006 | 78 |
| 2007 | 79 |
| 2008 | 71 |
| 2009 | 53 |
| 2010 | 55 |
| 2011 | 57 |
| 2012 | 65 |
| 2013 | 51 |
| 2014 | 51 |
| 2015 | 60 |
| 2016 | 129 |
| 2017 | 144 |
| 2018 | 43 |
| 2019 | 52 |
| 2020 | 60 |
| 2021 | 62 |
| 2022 | 60 |
| 2023 | 40 |
| 2024 | 40 |