Year Percent 1964-01-01 26.67740000000000 1965-01-01 25.36510000000000 1966-01-01 25.26260000000000 1967-01-01 27.98540000000000 1968-01-01 29.78630000000000 1969-01-01 30.95020000000000 1970-01-01 30.53810000000000 1971-01-01 33.48990000000000 1972-01-01 36.42750000000000 1973-01-01 35.74710000000000 1974-01-01 34.62290000000000 1975-01-01 34.43160000000000 1976-01-01 36.04870000000000 1977-01-01 37.94560000000000 1978-01-01 37.71330000000000 1979-01-01 36.67060000000000 1980-01-01 38.12690000000000 1981-01-01 38.93170000000000 1982-01-01 41.38340000000000 1983-01-01 46.94370000000000 1984-01-01 52.83080000000000 1985-01-01 57.41240000000000 1986-01-01 59.89540000000000 1987-01-01 60.77600000000000 1988-01-01 60.36240000000000 1989-01-01 62.31990000000000 1990-01-01 66.15660000000000 1991-01-01 70.97890000000000 1992-01-01 73.47490000000000 1993-01-01 77.20920000000000 1994-01-01 78.64200000000000 1995-01-01 78.37270000000000 1996-01-01 81.03130000000000 1997-01-01 91.38280000000000 1998-01-01 106.92100000000000 1999-01-01 109.78900000000000 2000-01-01 108.84500000000000 2001-01-01 109.18900000000000 2002-01-01 105.29200000000000 2003-01-01 104.80200000000000 2004-01-01 104.47300000000000 2005-01-01 100.75299999999999 2006-01-01 96.99840000000000 2007-01-01 91.71680000000000 2008-01-01 92.39370000000000 2009-01-01 92.45430000000000 2010-01-01 84.52150000000000 2011-01-01 89.05150000000000 2012-01-01 94.42380000000000 2013-01-01 103.01500000000000 2014-01-01 107.65299999999999 2015-01-01 108.20500000000000 2016-01-01 108.84600000000000