Year Percent 1960-01-01 8.3001300000000010000 1961-01-01 7.5306399999999990000 1962-01-01 6.2753600000000000000 1963-01-01 5.3973000000000000000 1964-01-01 4.8071699999999990000 1965-01-01 4.4563100000000000000 1966-01-01 4.7613800000000000000 1967-01-01 4.8975599999999995000 1968-01-01 5.1223100000000000000 1969-01-01 5.4743500000000000000 1970-01-01 5.5877000000000000000 1971-01-01 5.8128800000000010000 1972-01-01 5.4587900000000005000 1973-01-01 4.3716900000000000000 1974-01-01 4.9321500000000000000 1975-01-01 5.5026000000000000000 1976-01-01 5.0856000000000000000 1977-01-01 4.6178600000000000000 1978-01-01 4.4697500000000000000 1979-01-01 5.9491000000000000000 1980-01-01 6.3008000000000000000 1981-01-01 6.4621500000000000000 1982-01-01 7.2027000000000000000 1983-01-01 6.0752200000000000000 1984-01-01 6.2927000000000000000 1985-01-01 7.5645000000000000000 1986-01-01 7.9816199999999995000 1987-01-01 8.6849800000000000000 1988-01-01 8.1829300000000000000 1989-01-01 7.1275699999999995000 1990-01-01 5.2063200000000000000 1991-01-01 6.0945400000000000000 1992-01-01 9.0810600000000000000 1993-01-01 7.6434700000000000000 1994-01-01 5.3754800000000005000 1995-01-01 4.2401599999999995000 1996-01-01 3.3730900000000004000 1997-01-01 2.7819900000000000000 1998-01-01 2.0161800000000000000 1999-01-01 1.3544600000000000000 2000-01-01 1.0058400000000000000 2001-01-01 0.4222340000000000000 2002-01-01 0.0119300000000000000 2003-01-01 0.0061410000000000000 2004-01-01 0.0010360000000000000 2005-01-01 0.0011980000000000000 2006-01-01 0.0022600000000000003 2007-01-01 0.0010770000000000000 2008-01-01 0.0010770000000000000 2009-01-01 0.0010770000000000000 2010-01-01 0.0010770000000000000 2011-01-01 0.0010770000000000000 2012-01-01 0.0434590000000000000 2013-01-01 0.1751110000000000000 2014-01-01 0.2737110000000000400 2015-01-01 2.1111200000000000000 2016-01-01 5.2969900000000000000