| Year | Count |
|---|---|
| 1978 | 5 |
| 1986 | 5 |
| 1987 | 41 |
| 1988 | 8 |
| 1989 | 6 |
| 1990 | 5 |
| 1991 | 91 |
| 1992 | 244 |
| 1993 | 298 |
| 1994 | 323 |
| 1995 | 860 |
| 1996 | 867 |
| 1997 | 706 |
| 1998 | 1,273 |
| 1999 | 1,334 |
| 2000 | 789 |
| 2001 | 569 |
| 2002 | 374 |
| 2003 | 401 |
| 2004 | 490 |
| 2005 | 440 |
| 2006 | 349 |
| 2007 | 297 |
| 2008 | 300 |
| 2009 | 169 |
| 2010 | 121 |
| 2011 | 103 |
| 2012 | 63 |
| 2013 | 29 |
| 2014 | 41 |
| 2015 | 24 |
| 2016 | 22 |
| 2017 | 27 |
| 2018 | 16 |