Year Percent 1996-01-01 57.1730 1997-01-01 60.6061 1998-01-01 49.2308 1999-01-01 50.7246 2000-01-01 50.5952 2001-01-01 55.6452 2002-01-01 54.9865 2003-01-01 46.7470 2004-01-01 42.9194 2005-01-01 42.1136 2006-01-01 40.8046 2007-01-01 38.5528 2008-01-01 34.0206 2009-01-01 33.3716 2010-01-01 37.3152 2011-01-01 31.4708 2012-01-01 33.0002 2013-01-01 34.2839 2014-01-01 35.0766