Year Percent 1997-01-01 9.911200000000000 1998-01-01 9.610420000000000 1999-01-01 10.331400000000000 2000-01-01 9.332640000000000 2001-01-01 11.766300000000000 2002-01-01 15.088400000000000 2003-01-01 17.764100000000000 2004-01-01 19.462300000000000 2005-01-01 22.330300000000000 2006-01-01 26.866300000000000 2007-01-01 32.205300000000000 2008-01-01 35.080600000000000 2009-01-01 38.885100000000000 2010-01-01 41.773200000000000 2011-01-01 42.925100000000000 2012-01-01 43.910200000000000 2013-01-01 43.681800000000000 2014-01-01 46.251000000000005 2015-01-01 48.114700000000000