Year Percent 1960-01-01 14.920800000000000 1961-01-01 14.056300000000000 1962-01-01 14.611900000000000 1963-01-01 15.049400000000000 1964-01-01 16.776700000000000 1965-01-01 18.287500000000000 1966-01-01 20.828700000000000 1967-01-01 24.076999999999998 1968-01-01 24.828600000000000 1969-01-01 25.910800000000000 1970-01-01 23.498100000000000 1971-01-01 23.324900000000000 1972-01-01 24.591700000000000 1973-01-01 27.722400000000000 1974-01-01 28.725100000000000 1975-01-01 29.704900000000000 1976-01-01 31.680999999999997 1977-01-01 31.972800000000000 1978-01-01 39.308400000000000 1979-01-01 43.867200000000000 1980-01-01 43.879000000000000 1981-01-01 41.397000000000000 1982-01-01 42.265100000000000 1983-01-01 40.107500000000000 1984-01-01 37.681200000000000 1985-01-01 40.805500000000000 1986-01-01 40.762400000000000 1987-01-01 44.191800000000000 1988-01-01 46.967700000000000 1989-01-01 48.746400000000000 1990-01-01 47.261700000000000 1991-01-01 45.982900000000000 1992-01-01 46.773300000000000 1993-01-01 51.706400000000000 1994-01-01 54.192800000000000 1995-01-01 55.636700000000000 1996-01-01 58.152500000000000 1997-01-01 60.651400000000000 1998-01-01 62.590200000000000 1999-01-01 66.611700000000000 2000-01-01 68.276000000000010 2001-01-01 75.630800000000000 2002-01-01 81.624200000000000 2003-01-01 81.951000000000010 2004-01-01 78.127700000000000 2005-01-01 79.836600000000000 2006-01-01 80.865100000000000 2007-01-01 83.359600000000000 2008-01-01 90.339300000000000 2009-01-01 88.336900000000000 2010-01-01 85.125800000000000 2011-01-01 86.137600000000000 2012-01-01 75.938000000000000 2013-01-01 64.987100000000000 2014-01-01 64.635200000000000 2015-01-01 64.704900000000000 2016-01-01 64.453900000000000