Year Percent 1996-01-01 76.19780000000000 1997-01-01 73.40470000000000 1998-01-01 84.44740000000000 1999-01-01 80.35980000000000 2000-01-01 86.08730000000000 2001-01-01 86.32680000000000 2002-01-01 87.59090000000000 2003-01-01 84.57490000000000 2004-01-01 84.19030000000000 2005-01-01 86.47990000000000 2006-01-01 84.96799999999999 2007-01-01 85.36730000000000 2008-01-01 85.63280000000000 2009-01-01 85.67510000000000 2010-01-01 86.61100000000000 2011-01-01 86.20210000000000 2012-01-01 85.46040000000000 2013-01-01 82.86660000000000 2014-01-01 83.21160000000000 2015-01-01 78.49370000000000 2016-01-01 77.24620000000000