Year Percent 2000-01-01 19.91 2001-01-01 23.73 2002-01-01 28.43 2003-01-01 27.53 2004-01-01 31.38 2005-01-01 31.38 2006-01-01 31.38 2007-01-01 12.63 2008-01-01 9.75 2009-01-01 15.38 2010-01-01 14.14 2011-01-01 13.11 2012-01-01 13.99 2013-01-01 14.56 2014-01-01 15.63 2015-01-01 18.12 2016-01-01 20.97