| Year | Count |
|---|---|
| 1978 | 18 |
| 1979 | 266 |
| 1980 | 172 |
| 1981 | 51 |
| 1982 | 58 |
| 1983 | 59 |
| 1984 | 66 |
| 1985 | 56 |
| 1986 | 56 |
| 1987 | 61 |
| 1988 | 71 |
| 1989 | 72 |
| 1990 | 59 |
| 1991 | 62 |
| 1992 | 60 |
| 1993 | 66 |
| 1994 | 71 |
| 1995 | 45 |
| 1996 | 60 |
| 1997 | 40 |
| 1998 | 36 |
| 1999 | 32 |
| 2000 | 28 |
| 2001 | 31 |
| 2002 | 27 |
| 2003 | 23 |
| 2004 | 18 |
| 2005 | 18 |
| 2006 | 15 |
| 2007 | 16 |
| 2008 | 12 |
| 2009 | 9 |
| 2010 | 7 |
| 2011 | 7 |
| 2012 | 8 |
| 2013 | 6 |
| 2015 | 21 |
| 2016 | 15 |
| 2017 | 24 |