Year Percent 1960-01-01 0.1607350000000000 1961-01-01 1.1212400000000000 1962-01-01 3.1544600000000000 1963-01-01 6.2862700000000000 1964-01-01 8.0785500000000000 1965-01-01 9.6423000000000000 1966-01-01 12.2766000000000000 1967-01-01 17.2694000000000000 1968-01-01 19.0178000000000000 1969-01-01 16.5562000000000000 1970-01-01 9.9357300000000000 1971-01-01 11.0616000000000000 1972-01-01 10.8448000000000000 1973-01-01 8.0693600000000010 1974-01-01 7.5930100000000005 1975-01-01 10.2021000000000000 1976-01-01 12.4471000000000000 1977-01-01 14.4548000000000000 1978-01-01 10.9662000000000000 1979-01-01 11.7141000000000000 1980-01-01 9.5945200000000000 1981-01-01 9.0767700000000000 1982-01-01 8.8246800000000000 1983-01-01 8.2582000000000000 1984-01-01 8.0358300000000000 1985-01-01 9.3210300000000000 1986-01-01 9.5417399999999990 1987-01-01 11.9875000000000000 1988-01-01 11.6253000000000000 1989-01-01 9.1180500000000000 1990-01-01 7.7846899999999990 1991-01-01 7.7209100000000010 1992-01-01 8.9221600000000000 1993-01-01 11.2656000000000000 1994-01-01 11.5385000000000000 1995-01-01 10.7579000000000000 1996-01-01 9.1442199999999990 1997-01-01 8.5636600000000000 1998-01-01 23.4426000000000000 1999-01-01 40.3579000000000000 2000-01-01 44.7889999999999940 2001-01-01 24.4599000000000000 2002-01-01 20.2723000000000000 2003-01-01 20.7531000000000000 2004-01-01 7.9202000000000000 2005-01-01 8.3578000000000000 2006-01-01 7.6158500000000000 2007-01-01 8.4595000000000000 2008-01-01 9.8440400000000000 2009-01-01 8.9549000000000000 2010-01-01 6.5750100000000010 2011-01-01 6.1262400000000000 2012-01-01 6.8152700000000000 2013-01-01 8.7173400000000000 2014-01-01 11.9144000000000000 2015-01-01 11.6382000000000000 2016-01-01 9.5633500000000000