Year Percent 1960-01-01 2.7693700000000000 1961-01-01 3.1087599999999997 1962-01-01 4.0507400000000000 1963-01-01 5.6184300000000000 1964-01-01 6.8137500000000000 1965-01-01 6.1647200000000000 1966-01-01 5.7407400000000000 1967-01-01 5.6813000000000000 1968-01-01 5.3125000000000000 1969-01-01 4.8047000000000000 1970-01-01 4.0461800000000006 1971-01-01 3.9789500000000000 1972-01-01 4.0433100000000000 1973-01-01 4.4867400000000000 1974-01-01 4.7834200000000000 1975-01-01 4.5671900000000000 1976-01-01 4.4689600000000000 1977-01-01 4.4056500000000000 1978-01-01 4.6624600000000000 1979-01-01 4.0433500000000000 1980-01-01 4.2156800000000000 1981-01-01 4.2168199999999990 1982-01-01 4.0557600000000000 1983-01-01 3.5597900000000000 1984-01-01 2.2866000000000000 1985-01-01 1.3469400000000000 1986-01-01 1.1893000000000000 1987-01-01 1.2507800000000000 1988-01-01 1.4007700000000000 1989-01-01 1.7921900000000002 1990-01-01 1.9793500000000000 1991-01-01 1.6509000000000000 1992-01-01 1.8427300000000000 1993-01-01 1.9713900000000002 1994-01-01 2.0123500000000000 1995-01-01 1.7638200000000002 1996-01-01 1.5008400000000000 1997-01-01 1.8562500000000000 1998-01-01 1.6751400000000000 1999-01-01 1.4505299999999999 2000-01-01 1.3204700000000000 2001-01-01 1.3851300000000000 2002-01-01 1.5873600000000000 2003-01-01 2.1812099999999996 2004-01-01 2.8717400000000000 2005-01-01 3.2297400000000000 2006-01-01 3.0356300000000000 2007-01-01 3.4798400000000003 2008-01-01 4.5316300000000010 2009-01-01 6.0726800000000000 2010-01-01 6.7691399999999990 2011-01-01 6.8460199999999990 2012-01-01 6.0336900000000000 2013-01-01 4.7829000000000000 2014-01-01 4.6592600000000000 2015-01-01 5.1954500000000000 2016-01-01 5.0657300000000000