Year Percent 2005-01-01 78.1601367527375 2006-01-01 80.0767720969252 2007-01-01 78.3267717569282 2008-01-01 77.2091994760258 2009-01-01 75.8064591191102 2010-01-01 74.9088106498976 2011-01-01 74.6441313041539 2012-01-01 76.1725407588081 2013-01-01 75.5704016598976 2014-01-01 76.2894256260568 2015-01-01 75.8420796964342 2016-01-01 75.8111494164725 2017-01-01 76.4281706648839