Year Percent 1960-01-01 2.0288400000000000 1961-01-01 1.9927900000000000 1962-01-01 1.6774799999999999 1963-01-01 1.4245200000000000 1964-01-01 1.8044600000000000 1965-01-01 1.9741600000000000 1966-01-01 2.4245900000000002 1967-01-01 2.7748100000000000 1968-01-01 1.7169299999999998 1969-01-01 0.6097170000000000 1970-01-01 0.8664639999999999 1971-01-01 1.4456799999999999 1972-01-01 1.4742100000000000 1973-01-01 1.9108000000000000 1974-01-01 2.6620700000000000 1975-01-01 3.9585600000000000 1976-01-01 5.5914600000000000 1977-01-01 6.3562000000000000 1978-01-01 8.0582000000000000 1979-01-01 10.3949000000000000 1980-01-01 14.5723000000000000 1981-01-01 17.3305000000000000 1982-01-01 19.9805000000000000 1983-01-01 19.4670000000000000 1984-01-01 15.9387000000000000 1985-01-01 16.5908000000000000 1986-01-01 11.5974000000000000 1987-01-01 9.3292300000000000 1988-01-01 8.2357800000000000 1989-01-01 6.8432500000000000 1990-01-01 14.1016000000000000 1991-01-01 10.0242000000000000 1992-01-01 6.6076399999999990 1993-01-01 4.3643400000000000 1994-01-01 31.2832000000000000 1995-01-01 45.4488000000000000 1996-01-01 32.6422000000000000 1997-01-01 36.5628000000000000 1998-01-01 30.9848000000000000 1999-01-01 28.4473000000000000 2000-01-01 29.8795000000000000 2001-01-01 29.7013000000000000 2002-01-01 24.9631000000000000 2003-01-01 20.7221000000000000 2004-01-01 16.8093000000000000 2005-01-01 12.5183000000000000 2006-01-01 10.8570000000000010 2007-01-01 6.2700200000000000 2008-01-01 2.4241900000000003 2009-01-01 3.0382400000000000 2010-01-01 4.3739300000000005 2011-01-01 3.7546800000000005 2012-01-01 1.7045599999999999 2013-01-01 1.7343099999999998 2014-01-01 3.5072900000000002 2015-01-01 5.0704000000000000 2016-01-01 6.2005500000000000