Year Percent 1960-01-01 47.763900000000000 1961-01-01 45.730700000000000 1962-01-01 44.363200000000000 1963-01-01 45.891200000000000 1964-01-01 45.004100000000000 1965-01-01 44.097800000000000 1966-01-01 43.807100000000000 1967-01-01 43.751700000000000 1968-01-01 44.043000000000000 1969-01-01 42.620700000000000 1970-01-01 41.653800000000000 1971-01-01 40.032600000000000 1972-01-01 39.112800000000000 1973-01-01 38.367300000000000 1974-01-01 38.468200000000000 1975-01-01 40.525999999999996 1976-01-01 41.616300000000000 1977-01-01 40.836200000000000 1978-01-01 39.743400000000000 1979-01-01 38.760999999999996 1980-01-01 40.056400000000000 1981-01-01 40.604600000000000 1982-01-01 39.275900000000000 1983-01-01 42.421400000000000 1984-01-01 47.101900000000000 1985-01-01 51.235000000000000 1986-01-01 54.075600000000000 1987-01-01 55.474300000000000 1988-01-01 56.706100000000000 1989-01-01 55.559000000000000 1990-01-01 55.070400000000000 1991-01-01 55.812600000000000 1992-01-01 54.798000000000000 1993-01-01 59.445400000000000 1994-01-01 57.670300000000000 1995-01-01 53.974000000000000 1996-01-01 55.142900000000000 1997-01-01 56.239100000000000 1998-01-01 57.058000000000000 1999-01-01 55.192200000000000 2000-01-01 50.140400000000000 2001-01-01 48.071100000000000 2002-01-01 48.613100000000000 2003-01-01 50.237600000000000 2004-01-01 51.970600000000000 2005-01-01 56.113400000000000 2006-01-01 59.540700000000000 2007-01-01 63.668900000000000 2008-01-01 68.220800000000000 2009-01-01 70.970500000000000 2010-01-01 67.565800000000000 2011-01-01 66.853600000000000 2012-01-01 63.862400000000000 2013-01-01 60.036100000000000 2014-01-01 59.506200000000000 2015-01-01 65.094600000000000 2016-01-01 64.359400000000000