Year	Percent
1960-01-01	17.883100000000000
1961-01-01	17.905000000000000
1962-01-01	18.130800000000000
1963-01-01	18.094100000000000
1964-01-01	18.131300000000000
1965-01-01	17.672100000000000
1966-01-01	19.478900000000000
1967-01-01	19.331200000000000
1968-01-01	19.894200000000000
1969-01-01	20.895600000000000
1970-01-01	18.887000000000000
1971-01-01	19.023200000000000
1972-01-01	20.203100000000000
1973-01-01	20.580200000000000
1974-01-01	20.337400000000000
1975-01-01	20.734700000000000
1976-01-01	21.508500000000000
1977-01-01	22.494700000000000
1978-01-01	24.090500000000000
1979-01-01	25.956700000000000
1980-01-01	25.873600000000000
1981-01-01	25.286500000000000
1982-01-01	23.747800000000000
1983-01-01	21.740100000000000
1984-01-01	20.691999999999997
1985-01-01	19.908700000000000
1986-01-01	20.383000000000000
1987-01-01	20.088400000000000
1988-01-01	20.663800000000000
1989-01-01	20.676100000000000
1990-01-01	20.780000000000000
1991-01-01	21.073700000000000
1992-01-01	21.883700000000000
1993-01-01	21.334100000000000
1994-01-01	19.808300000000000
1995-01-01	18.296500000000000
1996-01-01	16.533600000000000
1997-01-01	15.281200000000000
1998-01-01	15.391700000000000
1999-01-01	14.867800000000000
2000-01-01	12.087900000000000
2001-01-01	14.071200000000000
2002-01-01	17.262100000000000
2003-01-01	17.911100000000000
2004-01-01	16.802300000000000
2005-01-01	14.887300000000000
2006-01-01	13.561700000000000
2007-01-01	12.307400000000000
2008-01-01	17.778000000000000
2009-01-01	26.758600000000000
2010-01-01	25.518200000000000
2011-01-01	24.471000000000000
2012-01-01	24.386200000000000
2013-01-01	25.261300000000000
2014-01-01	25.885800000000000
2015-01-01	27.411300000000000
2016-01-01	29.595600000000000