Year Percent 1990-01-01 18.690700000000000 1991-01-01 18.860200000000000 1992-01-01 27.243700000000000 1993-01-01 36.723800000000000 1994-01-01 37.973600000000000 1995-01-01 43.993200000000000 1996-01-01 44.228900000000000 1997-01-01 44.691800000000000 1998-01-01 46.968400000000000 1999-01-01 43.479600000000000 2000-01-01 36.911300000000000 2001-01-01 41.307100000000000 2002-01-01 38.608000000000004 2003-01-01 42.546200000000000 2004-01-01 43.466100000000000 2005-01-01 47.396900000000000 2006-01-01 47.539800000000000 2007-01-01 47.804600000000000 2008-01-01 46.532100000000000 2009-01-01 46.778700000000000 2010-01-01 46.274300000000000 2011-01-01 46.589200000000000 2012-01-01 44.903200000000000 2013-01-01 45.238000000000000 2014-01-01 46.591900000000000 2015-01-01 50.323300000000000 2016-01-01 51.836400000000000