Year Percent 1960-01-01 48.222700000000000 1961-01-01 46.885800000000000 1962-01-01 47.144900000000000 1963-01-01 46.350800000000000 1964-01-01 43.349400000000000 1965-01-01 43.035900000000000 1966-01-01 43.778800000000000 1967-01-01 44.008300000000000 1968-01-01 44.330300000000000 1969-01-01 43.994100000000000 1970-01-01 41.093900000000000 1971-01-01 42.116600000000000 1972-01-01 42.192900000000000 1973-01-01 42.017200000000000 1974-01-01 46.508600000000000 1975-01-01 46.854800000000000 1976-01-01 45.622600000000000 1977-01-01 42.226000000000006 1978-01-01 43.477100000000000 1979-01-01 45.992300000000000 1980-01-01 47.308200000000000 1981-01-01 47.340800000000000 1982-01-01 43.190400000000000 1983-01-01 38.992300000000000 1984-01-01 38.185400000000000 1985-01-01 38.086000000000000 1986-01-01 36.454400000000000 1987-01-01 35.632500000000000 1988-01-01 35.453200000000000 1989-01-01 33.572800000000000 1990-01-01 34.472800000000000 1991-01-01 36.920500000000000 1992-01-01 36.992600000000000 1993-01-01 39.857900000000000 1994-01-01 43.587200000000000 1995-01-01 51.929100000000000 1996-01-01 62.463700000000000 1997-01-01 63.846000000000004 1998-01-01 65.800900000000000 1999-01-01 69.219600000000000 2000-01-01 71.588200000000000 2001-01-01 67.608300000000000 2002-01-01 64.581400000000000 2003-01-01 67.251400000000000 2004-01-01 70.278300000000000 2005-01-01 72.673300000000000 2006-01-01 81.713800000000000 2007-01-01 91.587000000000000 2008-01-01 101.895000000000000 2009-01-01 108.589000000000000 2010-01-01 106.634000000000000 2011-01-01 98.465900000000000 2012-01-01 94.340000000000000 2013-01-01 95.348000000000000 2014-01-01 89.727600000000000 2015-01-01 68.296900000000000 2016-01-01 71.212600000000000