Year Percent 1996-01-01 44.8592 1997-01-01 48.9834 1998-01-01 60.2727 1999-01-01 73.3556 2000-01-01 70.3714 2001-01-01 70.7898 2002-01-01 68.9079 2003-01-01 66.1407 2004-01-01 62.0732 2005-01-01 57.5772 2006-01-01 58.8671 2007-01-01 58.4442 2008-01-01 58.7801 2009-01-01 59.2923 2010-01-01 56.6950 2011-01-01 55.5208 2012-01-01 54.2030 2013-01-01 51.2345 2014-01-01 52.3831 2015-01-01 52.3444 2016-01-01 52.3895