Year Percent 1965-01-01 5.6021100000000000 1966-01-01 5.2081700000000000 1967-01-01 5.7450100000000000 1968-01-01 6.7930300000000000 1969-01-01 7.8766399999999990 1970-01-01 4.7360300000000000 1971-01-01 4.9212600000000000 1972-01-01 5.4486200000000000 1973-01-01 4.9462500000000000 1974-01-01 4.7890000000000000 1975-01-01 5.0303100000000000 1976-01-01 5.7044100000000000 1977-01-01 6.5089200000000000 1978-01-01 7.5684700000000000 1979-01-01 11.8367000000000000 1980-01-01 10.0552000000000000 1981-01-01 9.7175300000000000 1982-01-01 9.3509200000000000 1983-01-01 9.1776300000000000 1984-01-01 8.2661900000000000 1985-01-01 6.5581500000000000 1986-01-01 5.9654800000000000 1987-01-01 5.1834900000000000 1988-01-01 4.0765000000000000 1989-01-01 4.6500500000000000 1990-01-01 5.7929699999999995 1991-01-01 5.5611100000000000 1992-01-01 6.9266600000000010 1993-01-01 5.2016400000000000 1994-01-01 4.9581599999999995 1995-01-01 3.4523200000000000 1996-01-01 2.2543200000000000 1997-01-01 2.0014000000000000 1998-01-01 2.5148400000000000 1999-01-01 2.7188300000000000 2000-01-01 2.6017700000000000 2001-01-01 2.8339900000000000 2002-01-01 2.5902000000000000 2003-01-01 2.7235300000000000 2004-01-01 3.0895900000000003 2005-01-01 3.5984500000000000 2006-01-01 4.1324200000000000 2007-01-01 4.9351000000000000 2008-01-01 6.6939600000000010 2009-01-01 9.2096100000000010 2010-01-01 11.3426000000000000 2011-01-01 12.6118000000000000 2012-01-01 12.8970000000000000 2013-01-01 11.5493000000000000 2014-01-01 10.6096000000000000 2015-01-01 10.4112000000000000 2016-01-01 9.9978000000000000