Year Percent 1995 23.2554 1996 21.42004 1997 20.42271 1998 20.10886 1999 19.69795 2000 18.46662 2001 17.23454 2002 17.07473 2003 17.63927 2004 17.24557 2005 17.96072 2006 16.75461 2007 16.7158 2008 16.40638 2009 15.48444 2010 14.99047 2011 15.50155 2012 14.97135 2013 15.92241 2014 16.69956 2015 17.59772 2016 17.44623