Year Percent 1960-01-01 8.2162200000000000 1961-01-01 8.8289200000000000 1962-01-01 12.5704000000000000 1963-01-01 17.5257000000000000 1964-01-01 15.2524000000000000 1965-01-01 14.6199000000000000 1966-01-01 13.7374000000000000 1967-01-01 13.6794000000000000 1968-01-01 13.9247000000000000 1969-01-01 14.2770000000000010 1970-01-01 5.2422400000000000 1971-01-01 5.8734800000000010 1972-01-01 6.3735700000000000 1973-01-01 7.4351300000000000 1974-01-01 8.8089800000000000 1975-01-01 9.2503900000000000 1976-01-01 10.2158000000000000 1977-01-01 15.4215000000000000 1978-01-01 22.4047000000000000 1979-01-01 18.4853000000000000 1980-01-01 14.0787000000000000 1981-01-01 13.8045000000000000 1982-01-01 14.1762000000000000 1983-01-01 14.7182000000000000 1984-01-01 15.4518000000000000 1985-01-01 16.6864000000000000 1986-01-01 19.0762000000000000 1987-01-01 28.0242000000000000 1988-01-01 18.7828000000000000 1989-01-01 14.1536000000000000 1990-01-01 13.1550000000000000 1991-01-01 13.6825000000000000 1992-01-01 12.0790000000000000 1993-01-01 9.9544100000000010 1994-01-01 7.3320600000000000 1995-01-01 6.7320400000000000 1996-01-01 6.2057199999999995 1997-01-01 7.0782800000000000 1998-01-01 10.0274000000000000 1999-01-01 9.3428899999999990 2000-01-01 7.8113899999999990 2001-01-01 9.4393100000000000 2002-01-01 10.7058000000000000 2003-01-01 10.6055000000000000 2004-01-01 8.6259900000000000 2005-01-01 7.2174200000000000 2006-01-01 7.8436600000000010 2007-01-01 9.5405900000000000 2008-01-01 8.8824899999999990 2009-01-01 9.3721199999999990 2010-01-01 7.4334600000000000 2011-01-01 7.3719399999999995 2012-01-01 9.8595600000000000 2013-01-01 12.8894000000000000 2014-01-01 14.5119000000000000 2015-01-01 14.8305000000000000 2016-01-01 14.3426000000000000