Year Percent 1995 15.64 1996 16.44 1997 15.07 1998 19.11 1999 16.91 2000 18.5 2001 18.62 2002 17.67 2003 16.67 2004 17.21 2005 16.95 2006 16.34 2007 15.66 2008 15.06 2009 16.44 2010 17.94