Year	Percent
1960-01-01	13.085200000000000
1961-01-01	12.678300000000000
1962-01-01	12.803500000000000
1963-01-01	12.726100000000000
1964-01-01	14.025900000000000
1965-01-01	15.195600000000000
1966-01-01	15.937000000000001
1967-01-01	17.000300000000000
1968-01-01	16.875500000000000
1969-01-01	17.312900000000000
1970-01-01	18.980400000000000
1971-01-01	20.036700000000000
1972-01-01	22.280000000000000
1973-01-01	23.345500000000000
1974-01-01	21.376500000000000
1975-01-01	21.953300000000000
1976-01-01	23.547700000000000
1977-01-01	23.381999999999998
1978-01-01	24.526300000000000
1979-01-01	23.818800000000000
1980-01-01	22.608700000000000
1981-01-01	23.605200000000000
1982-01-01	25.834000000000000
1983-01-01	26.841600000000000
1984-01-01	26.040600000000000
1985-01-01	27.087700000000000
1986-01-01	25.799600000000000
1987-01-01	25.196600000000000
1988-01-01	24.826100000000000
1989-01-01	24.727900000000000
1990-01-01	21.069200000000000
1991-01-01	20.873500000000000
1992-01-01	23.948200000000000
1993-01-01	22.972200000000000
1994-01-01	20.978000000000000
1995-01-01	19.938800000000000
1996-01-01	19.921600000000000
1997-01-01	20.447600000000000
1998-01-01	21.674500000000000
1999-01-01	22.442500000000000
2000-01-01	23.816500000000000
2001-01-01	23.411600000000000
2002-01-01	22.110500000000000
2003-01-01	27.826700000000000
2004-01-01	33.185600000000000
2005-01-01	34.635300000000000
2006-01-01	35.247600000000000
2007-01-01	34.340100000000000
2008-01-01	34.385300000000000
2009-01-01	35.876200000000000
2010-01-01	37.103800000000000
2011-01-01	36.357400000000000
2012-01-01	36.935100000000000
2013-01-01	38.141100000000000
2014-01-01	38.604100000000000
2015-01-01	38.513100000000000
2016-01-01	38.965700000000000