| Year | Count |
|---|---|
| 1978 | 10 |
| 1979 | 10 |
| 1981 | 20 |
| 1982 | 18 |
| 1984 | 9 |
| 1985 | 11 |
| 1986 | 27 |
| 1987 | 15 |
| 1988 | 29 |
| 1989 | 10 |
| 1990 | 8 |
| 1990 | 20 |
| 1991 | 5 |
| 1991 | 13 |
| 1992 | 5 |
| 1992 | 12 |
| 1993 | 5 |
| 1996 | 11 |
| 2000 | 38 |
| 2001 | 28 |
| 2002 | 52 |
| 2003 | 52 |
| 2004 | 42 |
| 2005 | 43 |
| 2006 | 51 |
| 2007 | 50 |
| 2008 | 106 |
| 2009 | 121 |
| 2010 | 91 |
| 2011 | 93 |
| 2012 | 72 |
| 2013 | 42 |
| 2014 | 14 |
| 2015 | 10 |
| 2016 | 10 |
| 2017 | 16 |
| 2018 | 20 |
| 2019 | 12 |
| 2021 | 5 |