Year Percent 1996-01-01 21.647400000000000 1997-01-01 31.858400000000000 1998-01-01 37.075000000000000 1999-01-01 39.987700000000000 2000-01-01 35.138700000000000 2001-01-01 42.353200000000000 2002-01-01 45.607400000000000 2003-01-01 43.752900000000000 2004-01-01 45.641200000000000 2005-01-01 51.532900000000000 2006-01-01 43.436300000000000 2007-01-01 40.624000000000000 2008-01-01 35.745300000000000 2009-01-01 31.706700000000000 2010-01-01 28.714000000000002 2011-01-01 24.775800000000000 2012-01-01 24.304100000000000 2013-01-01 25.441000000000000 2014-01-01 30.083400000000000