Year Percent 1965-01-01 61.1195 1966-01-01 59.5194 1967-01-01 57.8061 1968-01-01 58.7181 1969-01-01 58.7282 1970-01-01 50.0008 1971-01-01 48.8057 1972-01-01 50.4286 1973-01-01 54.0718 1974-01-01 54.2100 1975-01-01 55.2963 1976-01-01 55.5324 1977-01-01 54.6886 1978-01-01 53.5299 1979-01-01 52.1796 1980-01-01 46.7829 1981-01-01 48.5734 1982-01-01 49.7857 1983-01-01 49.5939 1984-01-01 49.2912 1985-01-01 50.2473 1986-01-01 48.0210 1987-01-01 46.6834 1988-01-01 47.6689 1989-01-01 49.3862 1990-01-01 49.5376 1991-01-01 49.4988 1992-01-01 48.9027 1993-01-01 44.7717 1994-01-01 44.1320 1995-01-01 45.6445 1996-01-01 46.3467 1997-01-01 48.9824 1998-01-01 51.9369 1999-01-01 53.0537 2000-01-01 51.3546 2001-01-01 47.1078 2002-01-01 40.6965 2003-01-01 39.9422 2004-01-01 38.1059 2005-01-01 38.8032 2006-01-01 40.5455 2007-01-01 41.5416 2008-01-01 43.8976 2009-01-01 43.9386 2010-01-01 40.1603 2011-01-01 39.2790 2012-01-01 39.8809 2013-01-01 39.6673 2014-01-01 40.6368 2015-01-01 42.0735 2016-01-01 43.1176