Year Percent 1998-01-01 52.2269 1999-01-01 54.0956 2000-01-01 47.3000 2001-01-01 36.4000 2002-01-01 42.0837 2003-01-01 19.0744 2004-01-01 29.5502 2005-01-01 42.7885 2006-01-01 47.4492 2007-01-01 52.5957 2008-01-01 42.0510 2009-01-01 47.6889 2010-01-01 54.3104 2011-01-01 56.1649 2012-01-01 58.7819 2013-01-01 54.0381 2014-01-01 54.2456 2015-01-01 54.6961 2016-01-01 55.3408