Year	Percent
1960-01-01	15.675900000000000
1961-01-01	14.863000000000000
1962-01-01	13.887600000000000
1963-01-01	13.368600000000000
1964-01-01	13.441400000000000
1965-01-01	14.527600000000000
1966-01-01	14.917900000000000
1967-01-01	14.946600000000000
1968-01-01	15.364200000000000
1969-01-01	16.273500000000000
1970-01-01	15.785800000000000
1971-01-01	15.902700000000000
1972-01-01	16.900200000000000
1973-01-01	17.342900000000000
1974-01-01	14.778100000000000
1975-01-01	20.180500000000000
1976-01-01	25.162200000000000
1977-01-01	27.534800000000000
1978-01-01	30.456800000000000
1979-01-01	27.812900000000000
1980-01-01	25.248600000000000
1981-01-01	25.415600000000000
1982-01-01	27.602200000000000
1983-01-01	29.981200000000000
1984-01-01	23.744600000000000
1985-01-01	24.389200000000000
1986-01-01	26.937800000000000
1987-01-01	25.830000000000000
1988-01-01	26.451500000000000
1989-01-01	18.942500000000000
1990-01-01	14.858900000000000
1991-01-01	15.403800000000000
1992-01-01	16.062900000000000
1993-01-01	14.923000000000000
1994-01-01	9.554730000000001
1995-01-01	7.243270000000000
1996-01-01	6.075360000000000
1997-01-01	9.155500000000000
1998-01-01	11.306400000000000
1999-01-01	10.680800000000000
2000-01-01	9.419310000000001
2001-01-01	10.490100000000000
2002-01-01	9.605250000000000
2003-01-01	8.158140000000000
2004-01-01	8.074130000000000
2005-01-01	10.123200000000000
2006-01-01	13.147600000000000
2007-01-01	22.752100000000000
2008-01-01	18.891900000000000
2009-01-01	21.604400000000000
2010-01-01	17.667200000000000
2011-01-01	17.117300000000000
2012-01-01	20.565000000000000
2013-01-01	23.776200000000000
2014-01-01	30.067900000000000
2015-01-01	30.352600000000000