Year Percent 1996-01-01 39.084200000000000 1997-01-01 30.935500000000000 1998-01-01 47.266400000000000 1999-01-01 44.126500000000000 2000-01-01 37.408200000000000 2001-01-01 27.958000000000002 2002-01-01 20.909400000000000 2003-01-01 22.261600000000000 2004-01-01 34.633500000000000 2005-01-01 28.728300000000000 2006-01-01 20.744400000000000 2007-01-01 18.885700000000000 2008-01-01 12.708500000000000 2009-01-01 18.145600000000000 2010-01-01 21.953900000000000 2011-01-01 20.543400000000000 2012-01-01 24.103200000000000 2013-01-01 21.404000000000000 2014-01-01 18.284700000000000 2015-01-01 22.745800000000000 2016-01-01 24.617800000000000