Year Percent 1960-01-01 23.44670000000000 1961-01-01 16.55190000000000 1962-01-01 11.96250000000000 1963-01-01 10.06350000000000 1964-01-01 8.93374000000000 1965-01-01 8.84463000000000 1966-01-01 8.22869000000000 1967-01-01 8.16288000000000 1968-01-01 7.90475000000000 1969-01-01 8.15440000000000 1970-01-01 6.35804000000000 1971-01-01 7.01520000000000 1972-01-01 6.54866000000000 1973-01-01 3.90150000000000 1974-01-01 2.62792000000000 1975-01-01 4.48782000000000 1976-01-01 5.51663000000000 1977-01-01 10.57850000000000 1978-01-01 15.50110000000000 1979-01-01 19.39290000000000 1980-01-01 29.41020000000000 1981-01-01 40.26190000000000 1982-01-01 54.70000000000000 1983-01-01 56.13860000000000 1984-01-01 54.77720000000000 1985-01-01 51.36740000000000 1986-01-01 45.57300000000000 1987-01-01 41.77820000000000 1988-01-01 39.35580000000000 1989-01-01 41.42530000000000 1990-01-01 43.05720000000000 1991-01-01 42.42460000000000 1992-01-01 45.36480000000000 1993-01-01 51.43670000000000 1994-01-01 55.28790000000000 1995-01-01 54.65990000000000 1996-01-01 58.61790000000000 1997-01-01 59.98710000000000 1998-01-01 61.40170000000000 1999-01-01 63.79940000000000 2000-01-01 64.68840000000000 2001-01-01 68.18330000000000 2002-01-01 70.18390000000000 2003-01-01 71.66620000000000 2004-01-01 70.03950000000000 2005-01-01 71.01030000000000 2006-01-01 70.33450000000000 2007-01-01 75.57190000000000 2008-01-01 86.18570000000000 2009-01-01 94.35160000000000 2010-01-01 93.45550000000000 2011-01-01 95.22960000000000 2012-01-01 99.21540000000000 2013-01-01 101.35600000000001 2014-01-01 103.21100000000000 2015-01-01 105.80700000000000 2016-01-01 108.56299999999999