Year | |
---|---|
1992 | 21.3 |
1993 | 20.9 |
1994 | 20.3 |
1995 | 21.1 |
1996 | 19.5 |
1997 | 17.4 |
1998 | 16.7 |
1999 | 16.2 |
2000 | 16.6 |
2001 | 15.0 |
2002 | 15.2 |
2003 | 16.5 |
2004 | 16.1 |
2005 | 16.4 |
2006 | 15.9 |
2007 | 16.7 |
2008 | 16.6 |
2009 | 16.5 |
2010 | 16.2 |
2011 | 15.9 |
2012 | 15.8 |
2013 | 15.7 |
2014 | 15.7 |
2015 | 15.5 |