Year Percent 1995 15.21 1996 15.38 1997 17.41 1998 18.93 1999 16.69 2000 17.83 2001 19.12 2002 17.83 2003 17.94 2004 18.82 2005 19.15 2006 18.03 2007 17.87 2008 15.2 2009 15.68 2010 13.55