Year Percent 2000 57.15587 2001 57.46333 2002 57.95336 2003 58.44133 2004 59.50972 2005 60.57694 2006 61.64257 2007 62.70681 2008 63.77039 2009 64.83276 2010 65.89391 2011 66.95218 2012 68.00757 2013 69.05954 2014 70.10704 2015 71.14958 2016 72.18666 2017 73.21776 2018 73.40682 2019 73.59587 2020 73.78451 2021 73.97233