Year Percent 1960-01-01 48.03990000000000 1961-01-01 48.27880000000000 1962-01-01 51.66770000000000 1963-01-01 54.16360000000000 1964-01-01 54.55290000000000 1965-01-01 55.74830000000000 1966-01-01 56.81200000000000 1967-01-01 57.81300000000000 1968-01-01 58.82520000000000 1969-01-01 54.66100000000000 1970-01-01 53.00710000000000 1971-01-01 55.60070000000000 1972-01-01 58.88990000000000 1973-01-01 59.46350000000000 1974-01-01 59.70420000000000 1975-01-01 61.48690000000000 1976-01-01 60.38280000000000 1977-01-01 60.36310000000000 1978-01-01 65.06520000000000 1979-01-01 69.36970000000000 1980-01-01 68.86070000000000 1981-01-01 66.74900000000000 1982-01-01 64.45650000000000 1983-01-01 64.42950000000000 1984-01-01 64.91170000000000 1985-01-01 65.32040000000000 1986-01-01 64.59740000000000 1987-01-01 65.31800000000000 1988-01-01 62.75750000000000 1989-01-01 61.22350000000000 1990-01-01 60.28600000000000 1991-01-01 59.00370000000000 1992-01-01 57.02210000000000 1993-01-01 57.99940000000000 1994-01-01 59.00590000000000 1995-01-01 62.11520000000000 1996-01-01 64.88920000000000 1997-01-01 66.28320000000000 1998-01-01 66.28320000000000 1999-01-01 66.28320000000000 2000-01-01 65.26790000000000 2001-01-01 62.23830000000000 2002-01-01 62.89850000000000 2003-01-01 66.62690000000000 2004-01-01 69.61290000000000 2005-01-01 72.26660000000000 2006-01-01 74.89940000000000 2007-01-01 77.93630000000000 2008-01-01 84.67440000000000 2009-01-01 90.61480000000000 2010-01-01 89.50330000000000 2011-01-01 88.14750000000000 2012-01-01 89.04700000000001 2013-01-01 89.87260000000000 2014-01-01 90.12820000000000 2015-01-01 91.20630000000000 2016-01-01 94.04020000000000