Year Percent 2002 87.10082 2003 88.16051 2004 88.94891 2005 88.28546 2006 87.56297 2007 88.50502 2008 88.6154 2009 89.25196 2010 89.10955 2011 89.16146 2012 89.06469 2013 89.73969 2014 90.34428 2015 90.20615 2016 90.87295 2017 91.82695