Year Percent 1999-01-01 21.4836 2000-01-01 20.5215 2001-01-01 15.3817 2002-01-01 13.1138 2003-01-01 19.3097 2004-01-01 22.0781 2005-01-01 24.0162 2006-01-01 26.3103 2007-01-01 28.5384 2008-01-01 13.5030 2009-01-01 25.7917 2010-01-01 28.6561 2011-01-01 22.8240 2012-01-01 24.2265 2013-01-01 23.4635 2014-01-01 25.0971 2015-01-01 22.1844 2016-01-01 30.0201