| Year | Count |
|---|---|
| 1979 | 18 |
| 1981 | 19 |
| 1982 | 23 |
| 1983 | 66 |
| 1984 | 108 |
| 1985 | 169 |
| 1986 | 173 |
| 1987 | 244 |
| 1988 | 263 |
| 1989 | 312 |
| 1990 | 257 |
| 1991 | 267 |
| 1992 | 217 |
| 1993 | 205 |
| 1994 | 235 |
| 1995 | 209 |
| 1996 | 207 |
| 1997 | 156 |
| 1998 | 132 |
| 1999 | 109 |
| 2000 | 127 |
| 2001 | 94 |
| 2002 | 94 |
| 2003 | 73 |
| 2004 | 63 |
| 2005 | 77 |
| 2006 | 58 |
| 2007 | 71 |
| 2008 | 40 |
| 2009 | 35 |
| 2010 | 37 |
| 2011 | 30 |
| 2012 | 26 |
| 2013 | 17 |
| 2014 | 22 |
| 2015 | 27 |
| 2016 | 15 |
| 2017 | 18 |