Year Percent 2000 81.97374 2001 82.31418 2002 82.65463 2003 82.99507 2004 83.33552 2005 83.67596 2006 84.0164 2007 84.35685 2008 84.69729 2009 85.03774 2010 85.37818 2011 85.71863 2012 86.05907 2013 86.39952 2014 86.39952 2015 86.39952