Year Percent 1999-01-01 23.1562 2000-01-01 23.0547 2001-01-01 20.2949 2002-01-01 17.3947 2003-01-01 20.5962 2004-01-01 23.3311 2005-01-01 20.1176 2006-01-01 25.5886 2007-01-01 28.0963 2008-01-01 14.4818 2009-01-01 21.3945 2010-01-01 16.8965 2011-01-01 14.1106 2012-01-01 17.6746 2013-01-01 24.5242 2014-01-01 24.0147 2015-01-01 25.5832 2016-01-01 24.8015