Year Percent 1960-01-01 23.7692 1961-01-01 20.9623 1962-01-01 21.5260 1963-01-01 15.2187 1964-01-01 18.7494 1965-01-01 21.2093 1966-01-01 21.9163 1967-01-01 20.9992 1968-01-01 22.8750 1969-01-01 21.6014 1970-01-01 16.6172 1971-01-01 19.2046 1972-01-01 21.5435 1973-01-01 21.7739 1974-01-01 21.1943 1975-01-01 21.2455 1976-01-01 21.7145 1977-01-01 24.5336 1978-01-01 24.3538 1979-01-01 21.9683 1980-01-01 21.2243 1981-01-01 21.1531 1982-01-01 20.9641 1983-01-01 20.5817 1984-01-01 22.1233 1985-01-01 24.8625 1986-01-01 26.5526 1987-01-01 27.1356 1988-01-01 28.8547 1989-01-01 30.5704 1990-01-01 31.4031 1991-01-01 31.9257 1992-01-01 34.3235 1993-01-01 37.2190 1994-01-01 40.4783 1995-01-01 42.7377 1996-01-01 43.5699 1997-01-01 45.7248 1998-01-01 50.7221 1999-01-01 54.2541 2000-01-01 53.2543 2001-01-01 54.1565 2002-01-01 55.6925 2003-01-01 61.0247 2004-01-01 67.1077 2005-01-01 70.0663 2006-01-01 69.3013 2007-01-01 68.6362 2008-01-01 76.8957 2009-01-01 82.8338 2010-01-01 82.4564 2011-01-01 86.6363 2012-01-01 93.5229 2013-01-01 101.4880 2014-01-01 102.7580 2015-01-01 100.4360 2016-01-01 97.6632