Year Percent 1983 84.31925 2004 77.05985 2005 74.98119 2006 76.38246 2007 75.58684 2008 84.37489 2009 85.63815 2010 80.99292 2011 81.86679 2012 81.23618 2013 82.40603 2014 73.46951 2015 77.48643 2016 72.40406