Year Percent 1960-01-01 26.365500000000000 1961-01-01 26.731500000000000 1962-01-01 25.326300000000000 1963-01-01 25.233600000000000 1964-01-01 27.378300000000000 1965-01-01 28.305600000000000 1966-01-01 27.482800000000000 1967-01-01 26.181700000000000 1968-01-01 25.282100000000000 1969-01-01 24.114600000000000 1970-01-01 23.546999999999997 1971-01-01 26.306400000000000 1972-01-01 27.202600000000000 1973-01-01 25.245400000000000 1974-01-01 25.685600000000000 1975-01-01 26.014100000000000 1976-01-01 25.652100000000000 1977-01-01 24.542400000000000 1978-01-01 25.693000000000000 1979-01-01 26.767700000000000 1980-01-01 26.423800000000000 1981-01-01 21.812700000000000 1982-01-01 17.564800000000000 1983-01-01 17.935000000000000 1984-01-01 18.400900000000000 1985-01-01 17.839200000000000 1986-01-01 16.496800000000000 1987-01-01 17.252400000000000 1988-01-01 16.666500000000000 1989-01-01 15.412600000000000 1990-01-01 14.597400000000000 1991-01-01 10.463300000000000 1992-01-01 10.667500000000000 1993-01-01 12.442100000000000 1994-01-01 12.872800000000000 1995-01-01 11.150200000000000 1996-01-01 11.396600000000000 1997-01-01 13.163300000000000 1998-01-01 15.773000000000000 1999-01-01 19.420700000000000 2000-01-01 22.785100000000000 2001-01-01 25.667100000000000 2002-01-01 27.720900000000000 2003-01-01 28.976000000000000 2004-01-01 29.493700000000000 2005-01-01 31.429300000000000 2006-01-01 33.514200000000000 2007-01-01 37.214500000000000 2008-01-01 43.356900000000000 2009-01-01 46.222400000000000 2010-01-01 43.460100000000000 2011-01-01 43.289300000000000 2012-01-01 44.881700000000000 2013-01-01 48.098400000000000 2014-01-01 50.462600000000000 2015-01-01 53.133999999999990 2016-01-01 55.902700000000000