Year Percent 1964-01-01 1.895574172810010 1965-01-01 1.785565982982240 1966-01-01 2.504895560958430 1967-01-01 1.878532197816480 1968-01-01 6.977107586729670 1969-01-01 2.315220566764750 1970-01-01 1.541865943256670 1971-01-01 0.316344463692509 1972-01-01 5.395935529334080 1973-01-01 13.450797872677600 1974-01-01 29.115630311092000 1975-01-01 14.738323271755000 1976-01-01 12.955729167183600 1977-01-01 9.172498970747990 1978-01-01 8.545139150822860 1979-01-01 14.466370205830300 1980-01-01 41.999514386569800 1981-01-01 14.461591074210600 1982-01-01 11.415693128365100 1983-01-01 5.589498018439470 1984-01-01 7.389162561694640 1985-01-01 6.698703946585000 1986-01-01 1.632653061224800 1987-01-01 0.518741633199869 1988-01-01 9.159314133510580 1989-01-01 12.670042091136000 1990-01-01 13.488088792637100 1991-01-01 7.001013775418850 1992-01-01 4.643519298837080 1993-01-01 10.517838447289600 1994-01-01 7.323471544122960 1995-01-01 6.029331884845300 1996-01-01 6.550973360655700 1997-01-01 6.833343349961050 1998-01-01 6.810793237971940 1999-01-01 6.909146248667770 2000-01-01 4.199288256228040 2001-01-01 5.389344262295100 2002-01-01 6.419333722211470 2003-01-01 3.921053575581930 2004-01-01 4.710370601058880 2005-01-01 4.937170049817840 2006-01-01 8.913501056501440 2007-01-01 8.827292723932970 2008-01-01 9.732283171468800 2009-01-01 2.516091281451130 2010-01-01 2.932363013698650 2011-01-01 6.522492548693390 2012-01-01 3.852160333159810 2013-01-01 3.543295739348350 2014-01-01 3.217691919946830 2015-01-01 1.286549707602350 2016-01-01 0.977675134719017 2017-01-01 3.666997026759170