Year Percent 1960-01-01 5.8164300000000000 1961-01-01 6.8277199999999990 1962-01-01 7.5363399999999990 1963-01-01 7.3787500000000000 1964-01-01 7.4068300000000000 1965-01-01 7.5256100000000000 1966-01-01 7.1295600000000010 1967-01-01 7.2961500000000000 1968-01-01 6.8205800000000005 1969-01-01 6.6194300000000000 1970-01-01 6.6957600000000010 1971-01-01 7.1151200000000000 1972-01-01 7.2480600000000010 1973-01-01 5.9901400000000000 1974-01-01 5.3506300000000010 1975-01-01 6.5514600000000000 1976-01-01 8.1155200000000000 1977-01-01 10.1459000000000000 1978-01-01 11.6442000000000000 1979-01-01 10.1326000000000000 1980-01-01 11.1295000000000000 1981-01-01 11.6577000000000000 1982-01-01 12.0638000000000000 1983-01-01 11.1979000000000000 1984-01-01 12.4858000000000000 1985-01-01 14.0801000000000000 1986-01-01 10.3745000000000000 1987-01-01 6.0670300000000000 1988-01-01 4.3054600000000000 1989-01-01 2.7507400000000000 1990-01-01 1.5626900000000000 1991-01-01 1.7053599999999998 1992-01-01 2.8679799999999998 1993-01-01 3.7150300000000005 1994-01-01 4.2113000000000000 1995-01-01 4.4535500000000000 1996-01-01 4.4973600000000000 1997-01-01 3.1990300000000000 1998-01-01 1.3598200000000000 1999-01-01 0.8449629999999999 2000-01-01 0.7122180000000000 2001-01-01 6.0478900000000000 2002-01-01 9.4081700000000000 2003-01-01 6.4593400000000000 2004-01-01 4.4639100000000000 2005-01-01 3.1728900000000000 2006-01-01 2.4445700000000000 2007-01-01 2.0435400000000000 2008-01-01 1.5707400000000000 2009-01-01 1.2350500000000000 2010-01-01 0.9384860000000000 2011-01-01 0.7530530000000000 2012-01-01 0.6966140000000001 2013-01-01 0.6483000000000000 2014-01-01 0.6116900000000000 2015-01-01 0.5416540000000000 2016-01-01 0.5895610000000000