Year Percent 1960-01-01 52.03070000000000 1961-01-01 56.91470000000000 1962-01-01 62.39010000000000 1963-01-01 67.58000000000000 1964-01-01 69.81560000000000 1965-01-01 69.45630000000000 1966-01-01 70.25870000000000 1967-01-01 69.72550000000000 1968-01-01 66.00640000000000 1969-01-01 62.88320000000000 1970-01-01 64.72420000000000 1971-01-01 66.87720000000000 1972-01-01 65.41560000000000 1973-01-01 69.19580000000000 1974-01-01 63.33800000000000 1975-01-01 56.44090000000000 1976-01-01 55.98250000000000 1977-01-01 56.94140000000000 1978-01-01 60.30220000000000 1979-01-01 63.22210000000000 1980-01-01 68.36560000000000 1981-01-01 71.99030000000000 1982-01-01 72.43150000000000 1983-01-01 75.26700000000000 1984-01-01 78.45960000000000 1985-01-01 81.32830000000000 1986-01-01 80.37650000000000 1987-01-01 77.18770000000000 1988-01-01 77.12680000000000 1989-01-01 78.82300000000001 1990-01-01 95.32260000000000 1991-01-01 127.66600000000000 1992-01-01 122.43000000000000 1993-01-01 110.36700000000000 1994-01-01 107.18100000000000 1995-01-01 115.71100000000000 1996-01-01 126.57400000000000 1997-01-01 136.66000000000000 1998-01-01 137.26600000000000 1999-01-01 124.52500000000000 2000-01-01 114.07100000000000 2001-01-01 106.36300000000000 2002-01-01 101.07700000000001 2003-01-01 99.96500000000000 2004-01-01 96.75080000000000 2005-01-01 96.12130000000000 2006-01-01 95.02410000000000 2007-01-01 91.71220000000000 2008-01-01 90.09730000000000 2009-01-01 88.11220000000000 2010-01-01 87.97410000000000 2011-01-01 87.98350000000000 2012-01-01 88.12630000000000 2013-01-01 90.31370000000000 2014-01-01 92.80390000000000 2015-01-01 96.57180000000000 2016-01-01 100.44900000000000