| Year | Count |
|---|---|
| 1979 | 5 |
| 1980 | 5 |
| 1981 | 5 |
| 1982 | 18 |
| 1983 | 9 |
| 1985 | 16 |
| 1986 | 22 |
| 1987 | 61 |
| 1988 | 29 |
| 1989 | 20 |
| 1990 | 80 |
| 1991 | 173 |
| 1992 | 194 |
| 1993 | 166 |
| 1994 | 258 |
| 1995 | 309 |
| 1996 | 266 |
| 1997 | 290 |
| 1998 | 230 |
| 1999 | 109 |
| 2000 | 82 |
| 2001 | 106 |
| 2002 | 53 |
| 2003 | 36 |
| 2004 | 87 |
| 2005 | 60 |
| 2006 | 37 |
| 2007 | 28 |
| 2008 | 31 |
| 2009 | 10 |
| 2010 | 8 |
| 2016 | 5 |