| Year | Count |
|---|---|
| 1987 | 6 |
| 1988 | 16 |
| 1990 | 17 |
| 1991 | 22 |
| 1992 | 6 |
| 1993 | 20 |
| 1994 | 31 |
| 1995 | 89 |
| 1996 | 74 |
| 1997 | 151 |
| 1998 | 149 |
| 1999 | 194 |
| 2000 | 180 |
| 2001 | 236 |
| 2002 | 220 |
| 2003 | 320 |
| 2004 | 310 |
| 2005 | 351 |
| 2006 | 308 |
| 2007 | 303 |
| 2008 | 275 |
| 2009 | 264 |
| 2010 | 259 |
| 2011 | 181 |
| 2012 | 160 |
| 2013 | 116 |
| 2014 | 71 |
| 2015 | 74 |
| 2016 | 60 |
| 2017 | 65 |
| 2018 | 24 |
| 2020 | 18 |
| 2022 | 10 |