| Year | Count |
|---|---|
| 1974 | 7 |
| 1975 | 23 |
| 1976 | 42 |
| 1977 | 38 |
| 1978 | 31 |
| 1979 | 31 |
| 1980 | 12 |
| 1981 | 6 |
| 1982 | 9 |
| 1983 | 11 |
| 1984 | 24 |
| 1986 | 22 |
| 1988 | 6 |
| 1991 | 14 |
| 1992 | 7 |
| 1994 | 8 |
| 1999 | 12 |
| 2000 | 16 |
| 2001 | 11 |
| 2002 | 10 |
| 2003 | 39 |
| 2004 | 42 |
| 2005 | 87 |
| 2006 | 59 |
| 2007 | 69 |
| 2008 | 51 |
| 2009 | 39 |
| 2010 | 45 |
| 2011 | 22 |
| 2013 | 20 |
| 2014 | 12 |