Year Percent 1960-01-01 42.024600000000000 1961-01-01 39.920200000000000 1962-01-01 41.255100000000000 1963-01-01 42.280700000000000 1964-01-01 44.328700000000000 1965-01-01 47.070800000000000 1966-01-01 46.684100000000000 1967-01-01 47.587100000000000 1968-01-01 50.030200000000000 1969-01-01 51.982000000000000 1970-01-01 54.585100000000000 1971-01-01 59.111999999999995 1972-01-01 62.856900000000000 1973-01-01 64.798200000000000 1974-01-01 64.240100000000000 1975-01-01 65.952500000000000 1976-01-01 65.656900000000000 1977-01-01 62.183100000000000 1978-01-01 59.429900000000000 1979-01-01 60.324200000000000 1980-01-01 61.653100000000000 1981-01-01 63.843000000000000 1982-01-01 64.780000000000000 1983-01-01 59.832200000000000 1984-01-01 53.133000000000000 1985-01-01 51.641500000000000 1986-01-01 54.733200000000000 1987-01-01 57.022500000000000 1988-01-01 55.748999999999995 1989-01-01 55.372900000000000 1990-01-01 56.111800000000000 1991-01-01 57.901000000000000 1992-01-01 58.291200000000000 1993-01-01 60.041600000000000 1994-01-01 61.231200000000000 1995-01-01 60.808600000000000 1996-01-01 59.669900000000000 1997-01-01 56.660800000000000 1998-01-01 55.411500000000000 1999-01-01 65.121900000000000 2000-01-01 74.098800000000000 2001-01-01 77.878400000000000 2002-01-01 75.916400000000000 2003-01-01 75.061300000000000 2004-01-01 74.624000000000000 2005-01-01 76.156700000000000 2006-01-01 78.918700000000000 2007-01-01 81.504900000000000 2008-01-01 91.240800000000000 2009-01-01 99.190100000000000 2010-01-01 97.206500000000000 2011-01-01 94.977500000000000 2012-01-01 95.127300000000000 2013-01-01 95.721300000000000 2014-01-01 95.318200000000000 2015-01-01 95.603900000000000 2016-01-01 96.845400000000000