Year Percent 1995 15.36 1996 15.54 1997 15.26 1998 14.4 1999 15 2000 15.15 2001 14.96 2002 14.54 2003 16.04 2004 15.66 2005 15.31 2006 14.36 2007 13.9 2008 14.4 2009 12.33 2010 15.16