| Year | Count |
|---|---|
| 1977 | 30 |
| 1978 | 5 |
| 1979 | 5 |
| 1980 | 21 |
| 1982 | 29 |
| 1983 | 45 |
| 1984 | 37 |
| 1985 | 34 |
| 1986 | 45 |
| 1987 | 80 |
| 1988 | 81 |
| 1989 | 115 |
| 1990 | 102 |
| 1991 | 158 |
| 1992 | 263 |
| 1993 | 189 |
| 1994 | 139 |
| 1995 | 107 |
| 1996 | 137 |
| 1997 | 90 |
| 1998 | 49 |
| 1999 | 69 |
| 2000 | 126 |
| 2001 | 49 |
| 2002 | 28 |
| 2003 | 37 |
| 2004 | 37 |
| 2005 | 24 |
| 2006 | 64 |
| 2007 | 36 |
| 2008 | 14 |
| 2009 | 17 |
| 2010 | 15 |
| 2011 | 10 |
| 2012 | 16 |
| 2013 | 10 |
| 2014 | 10 |
| 2015 | 5 |