Year Percent 1962-01-01 6.7232000000000000 1963-01-01 7.2589200000000000 1964-01-01 7.2028700000000000 1965-01-01 7.6382600000000010 1966-01-01 7.9197899999999990 1967-01-01 8.8910700000000000 1968-01-01 9.5553700000000000 1969-01-01 10.2951000000000000 1970-01-01 7.6269100000000005 1971-01-01 8.0245500000000000 1972-01-01 8.7216300000000010 1973-01-01 8.9342500000000000 1974-01-01 8.6469200000000000 1975-01-01 8.3984100000000000 1976-01-01 9.3330800000000000 1977-01-01 10.6246000000000000 1978-01-01 11.9885000000000000 1979-01-01 11.3095000000000000 1980-01-01 10.7812000000000000 1981-01-01 11.7492000000000000 1982-01-01 11.2241000000000000 1983-01-01 9.0737300000000000 1984-01-01 8.6298000000000000 1985-01-01 9.2705399999999990 1986-01-01 10.1800000000000000 1987-01-01 9.6888399999999990 1988-01-01 9.6267400000000000 1989-01-01 10.4409999999999990 1990-01-01 11.1392000000000000 1991-01-01 12.1671000000000000 1992-01-01 13.8068000000000000 1993-01-01 14.8956000000000000 1994-01-01 15.1438000000000000 1995-01-01 13.4047000000000000 1996-01-01 12.6428000000000000 1997-01-01 13.3316000000000000 1998-01-01 13.1890000000000000 1999-01-01 12.5822000000000000 2000-01-01 13.0267000000000000 2001-01-01 13.8052000000000000 2002-01-01 16.9388000000000000 2003-01-01 15.0351000000000000 2004-01-01 15.0132000000000000 2005-01-01 13.9389000000000000 2006-01-01 13.7061000000000000 2007-01-01 14.8579000000000000 2008-01-01 14.9548000000000000 2009-01-01 16.2562000000000000 2010-01-01 16.4116000000000000 2011-01-01 16.6419000000000000 2012-01-01 16.9074000000000000 2013-01-01 16.6820000000000020 2014-01-01 16.2237000000000000 2015-01-01 16.6146000000000000 2016-01-01 17.3678000000000000