Year Percent 1983-01-01 20.524700000000000 1984-01-01 19.302500000000000 1985-01-01 19.867300000000000 1986-01-01 20.667800000000000 1987-01-01 17.700300000000000 1988-01-01 17.610000000000000 1989-01-01 20.099700000000000 1990-01-01 21.218200000000000 1991-01-01 22.821400000000000 1992-01-01 25.061300000000000 1993-01-01 26.092700000000000 1994-01-01 27.587500000000000 1995-01-01 30.623600000000000 1996-01-01 32.058100000000000 1997-01-01 36.716500000000000 1998-01-01 41.710800000000000 1999-01-01 43.668100000000000 2000-01-01 43.290000000000000 2001-01-01 48.766300000000000 2002-01-01 49.717300000000000 2003-01-01 49.466900000000000 2004-01-01 49.638300000000000 2005-01-01 51.625000000000000 2006-01-01 52.140500000000000 2007-01-01 50.362500000000000 2008-01-01 58.389200000000000 2009-01-01 69.594500000000000 2010-01-01 73.129700000000000 2011-01-01 68.065500000000000 2012-01-01 62.814100000000000 2013-01-01 58.677800000000000 2014-01-01 60.443000000000005 2015-01-01 61.015600000000000 2016-01-01 62.056300000000000