Year Percent 1960-01-01 4.8690200000000000 1961-01-01 5.4446400000000000 1962-01-01 6.9716100000000010 1963-01-01 7.1325800000000000 1964-01-01 6.2329200000000000 1965-01-01 8.6257200000000000 1966-01-01 8.9676000000000000 1967-01-01 8.8974700000000000 1968-01-01 8.1362200000000000 1969-01-01 8.8182800000000000 1970-01-01 10.1875000000000000 1971-01-01 8.8518500000000000 1972-01-01 8.1084600000000010 1973-01-01 5.8709200000000000 1974-01-01 2.5729200000000000 1975-01-01 2.8481000000000000 1976-01-01 1.9918300000000000 1977-01-01 1.9918300000000000 1978-01-01 1.9918300000000000 1979-01-01 1.9918300000000000 1980-01-01 1.9918300000000000 1981-01-01 1.9918300000000000 1982-01-01 1.9918300000000000 1983-01-01 1.9918300000000000 1984-01-01 1.9918300000000000 1985-01-01 1.9918300000000000 1986-01-01 1.9918300000000000 1987-01-01 1.9918300000000000 1988-01-01 1.9918300000000000 1989-01-01 1.9918300000000000 1990-01-01 1.9918300000000000 1991-01-01 1.9918300000000000 1992-01-01 1.9918300000000000 1993-01-01 1.9918300000000000 1994-01-01 1.9918300000000000 1995-01-01 1.9918300000000000 1996-01-01 1.9918300000000000 1997-01-01 1.9918300000000000 1998-01-01 1.9918300000000000 1999-01-01 1.9918300000000000 2000-01-01 1.9918300000000000 2001-01-01 1.9918300000000000 2002-01-01 1.9918300000000000 2003-01-01 1.9918300000000000 2004-01-01 1.9918300000000000 2005-01-01 1.9918300000000000 2006-01-01 6.7847600000000000 2007-01-01 5.5068699999999990 2008-01-01 3.2240400000000000 2009-01-01 3.0593800000000000 2010-01-01 2.5960000000000000 2011-01-01 1.8817000000000000 2012-01-01 1.3547500000000000 2013-01-01 1.0819800000000000 2014-01-01 0.9576360000000000 2015-01-01 2.6564200000000002 2016-01-01 7.1520500000000000