Year Percent 2000 54.79053 2001 55.77697 2002 56.747 2003 57.69924 2004 58.63359 2005 59.54838 2006 60.44434 2007 61.32078 2008 62.17771 2009 63.01432 2010 63.83119 2011 64.62837 2012 65.40607 2013 66.04694 2014 66.11511 2015 66.18252 2016 66.24854 2017 66.31279