Year Percent 1998-01-01 41.6358 1999-01-01 41.1842 2000-01-01 41.9000 2001-01-01 40.0000 2002-01-01 41.3502 2003-01-01 51.6348 2004-01-01 52.1709 2005-01-01 60.7788 2006-01-01 62.4575 2007-01-01 67.9783 2008-01-01 56.3102 2009-01-01 66.9806 2010-01-01 71.8567 2011-01-01 74.3270 2012-01-01 73.6566 2013-01-01 73.0991 2014-01-01 72.3006 2015-01-01 73.4176 2016-01-01 73.4699