Year Percent 1999-01-01 33.333300000000000 2000-01-01 38.888900000000000 2001-01-01 26.923100000000000 2002-01-01 7.692310000000001 2003-01-01 19.354800000000000 2004-01-01 20.339000000000002 2005-01-01 23.728800000000000 2006-01-01 26.153800000000000 2007-01-01 34.146300000000000 2008-01-01 38.738700000000000 2009-01-01 37.894700000000000 2010-01-01 39.393900000000000 2011-01-01 40.217400000000000 2012-01-01 36.956500000000000 2013-01-01 36.734700000000000 2014-01-01 40.594100000000000