Year Percent 2000 38.68913 2001 38.08038 2002 37.47163 2003 36.86288 2004 36.25413 2005 35.64538 2006 35.03663 2007 34.42788 2008 33.81912 2009 33.21037 2010 32.60162 2011 31.99287 2012 31.38412 2013 30.77537 2014 30.77537 2015 30.77537 2016 30.77537 2017 30.77537