Year Percent 1960-01-01 19.0221 1961-01-01 19.7164 1962-01-01 21.7532 1963-01-01 21.4692 1964-01-01 21.4844 1965-01-01 20.3088 1966-01-01 20.9969 1967-01-01 22.1122 1968-01-01 22.8552 1969-01-01 23.0262 1970-01-01 20.0093 1971-01-01 19.1830 1972-01-01 19.2439 1973-01-01 18.5662 1974-01-01 16.2094 1975-01-01 15.2004 1976-01-01 16.6271 1977-01-01 18.3288 1978-01-01 19.8004 1979-01-01 19.3370 1980-01-01 19.9054 1981-01-01 20.4925 1982-01-01 21.5969 1983-01-01 23.5971 1984-01-01 24.3889 1985-01-01 24.8644 1986-01-01 24.5714 1987-01-01 23.4662 1988-01-01 24.2046 1989-01-01 25.9896 1990-01-01 27.4464 1991-01-01 29.6782 1992-01-01 31.1633 1993-01-01 34.3032 1994-01-01 38.9191 1995-01-01 42.7200 1996-01-01 46.4215 1997-01-01 50.8061 1998-01-01 53.9100 1999-01-01 54.8627 2000-01-01 55.2888 2001-01-01 54.2242 2002-01-01 53.6754 2003-01-01 52.9400 2004-01-01 50.1867 2005-01-01 48.9971 2006-01-01 50.3891 2007-01-01 50.8769 2008-01-01 54.0059 2009-01-01 59.7980 2010-01-01 58.3961 2011-01-01 58.9524 2012-01-01 57.2970 2013-01-01 61.6481 2014-01-01 68.0664 2015-01-01 71.0369 2016-01-01 72.5689