Year Percent 1973-01-01 20.440900000000000 1974-01-01 21.769700000000000 1975-01-01 22.617800000000000 1976-01-01 23.703300000000000 1977-01-01 26.101900000000000 1978-01-01 37.802900000000000 1979-01-01 47.060700000000000 1980-01-01 47.045100000000000 1981-01-01 49.585000000000000 1982-01-01 50.698100000000000 1983-01-01 53.427800000000000 1984-01-01 52.929200000000000 1985-01-01 53.497600000000000 1986-01-01 56.515800000000000 1987-01-01 60.026100000000000 1988-01-01 58.720200000000000 1989-01-01 60.733999999999995 1990-01-01 61.230000000000000 1991-01-01 55.815600000000000 1992-01-01 55.257100000000000 1993-01-01 58.180800000000000 1994-01-01 57.635500000000000 1995-01-01 57.457500000000000 1996-01-01 58.498600000000000 1997-01-01 57.269600000000000 1998-01-01 56.951400000000000 1999-01-01 60.261700000000000 2000-01-01 68.516800000000000 2001-01-01 78.360100000000000 2002-01-01 77.459600000000000 2003-01-01 75.763600000000000 2004-01-01 75.645300000000000 2005-01-01 85.441100000000000 2006-01-01 89.987800000000000 2007-01-01 93.784500000000000 2008-01-01 100.842000000000010 2009-01-01 105.393999999999990 2010-01-01 125.170000000000000 2011-01-01 148.696000000000000 2012-01-01 144.212000000000020 2013-01-01 133.551000000000020 2014-01-01 130.510000000000000 2015-01-01 128.235000000000000 2016-01-01 122.387000000000000