Year Percent 1995-01-01 52.8187502250000 1996-01-01 52.5553557100000 1997-01-01 51.9343260700000 1998-01-01 51.5080271275000 1999-01-01 51.7810022050000 2000-01-01 52.4502111625000 2001-01-01 52.1055460325000 2002-01-01 51.4511916250000 2003-01-01 51.5661076625000 2004-01-01 52.2159656100000 2005-01-01 53.3131219400000 2006-01-01 54.1625699825000 2007-01-01 55.4828554850000 2008-01-01 56.5027051225000 2009-01-01 56.0416335625000 2010-01-01 57.0378457000000 2011-01-01 57.7289360350000 2012-01-01 63.0666666666667 2013-01-01 63.6666666666667 2014-01-01 64.4416666666667 2015-01-01 64.7833333333333 2016-01-01 65.1416666666667 2017-01-01 65.3750000000000