Year Percent 1996-01-01 92.84290000000000 1997-01-01 91.62110000000000 1998-01-01 87.25620000000000 1999-01-01 87.89240000000000 2000-01-01 71.70010000000000 2001-01-01 69.54570000000000 2002-01-01 71.08040000000000 2003-01-01 70.15130000000000 2004-01-01 71.09910000000000 2005-01-01 72.56750000000000 2006-01-01 76.09190000000000 2007-01-01 76.49600000000001 2008-01-01 74.99180000000000 2009-01-01 74.51130000000000 2010-01-01 75.88080000000000 2011-01-01 75.24590000000000 2012-01-01 77.48170000000000 2013-01-01 79.52700000000000 2014-01-01 82.20790000000000 2015-01-01 79.35770000000000 2016-01-01 75.25190000000000