| Year | Count |
|---|---|
| 1967 | 10 |
| 1971 | 20 |
| 1973 | 10 |
| 1978 | 32 |
| 1979 | 12 |
| 1979 | 15 |
| 1984 | 12 |
| 1986 | 6 |
| 1988 | 14 |
| 1992 | 32 |
| 1993 | 5 |
| 1994 | 72 |
| 1995 | 86 |
| 1996 | 17 |
| 1997 | 21 |
| 1998 | 42 |
| 1999 | 294 |
| 2000 | 288 |
| 2001 | 228 |
| 2002 | 146 |
| 2003 | 155 |
| 2004 | 132 |
| 2005 | 163 |
| 2006 | 179 |
| 2007 | 149 |
| 2008 | 137 |
| 2009 | 108 |
| 2010 | 62 |
| 2011 | 91 |
| 2012 | 97 |
| 2013 | 55 |
| 2014 | 45 |
| 2015 | 20 |
| 2017 | 18 |
| 2018 | 20 |
| 2019 | 16 |
| 2020 | 23 |
| 2021 | 11 |