Year Percent 1996-01-01 90.33800000000000 1997-01-01 79.24380000000000 1998-01-01 75.65330000000000 1999-01-01 87.31100000000000 2000-01-01 87.36660000000000 2001-01-01 85.65700000000001 2002-01-01 87.51260000000000 2003-01-01 87.06560000000000 2004-01-01 86.62470000000000 2005-01-01 76.05180000000000 2006-01-01 77.53630000000000 2007-01-01 80.34530000000000 2008-01-01 80.58020000000000 2009-01-01 82.99410000000000 2010-01-01 83.96440000000000 2011-01-01 84.31000000000000 2012-01-01 84.72990000000000 2013-01-01 88.51620000000000 2014-01-01 88.58040000000000 2015-01-01 88.34320000000000 2016-01-01 89.52300000000000