Year Percent 1971-01-01 8.638639999999999 1972-01-01 9.096300000000000 1973-01-01 8.908780000000000 1974-01-01 8.993560000000000 1975-01-01 9.308810000000001 1976-01-01 9.663190000000000 1977-01-01 10.002100000000000 1978-01-01 10.115100000000000 1979-01-01 10.323800000000000 1980-01-01 10.988500000000000 1981-01-01 11.574500000000000 1982-01-01 12.296600000000000 1983-01-01 13.033100000000000 1984-01-01 13.341400000000000 1985-01-01 13.449100000000000 1986-01-01 14.103500000000000 1987-01-01 15.539400000000000 1988-01-01 17.092800000000000 1989-01-01 18.924700000000000 1990-01-01 20.642700000000000 1991-01-01 22.304600000000000 1992-01-01 24.050800000000000 1993-01-01 26.097900000000000 1994-01-01 28.021100000000000 1995-01-01 29.688500000000000 1996-01-01 30.917100000000000 1997-01-01 42.696500000000000 1998-01-01 56.351500000000000 1999-01-01 61.253000000000000 2000-01-01 63.198100000000000 2001-01-01 161.688000000000000 2002-01-01 165.558000000000000 2003-01-01 168.828000000000000 2004-01-01 166.148000000000000 2005-01-01 162.292000000000000 2006-01-01 156.804000000000000 2007-01-01 147.205000000000000 2008-01-01 143.323999999999980 2009-01-01 146.119000000000000 2010-01-01 142.024000000000000 2011-01-01 142.620000000000000 2012-01-01 141.757000000000000 2013-01-01 140.947000000000000 2014-01-01 141.696000000000000 2015-01-01 139.219000000000000 2016-01-01 135.311000000000000