Year	Percent
1960-01-01	19.150600000000000
1961-01-01	17.872100000000000
1962-01-01	18.016800000000000
1963-01-01	18.282200000000000
1964-01-01	17.337500000000000
1965-01-01	16.725100000000000
1966-01-01	15.332000000000000
1967-01-01	12.590800000000000
1968-01-01	13.290300000000000
1969-01-01	15.162600000000000
1970-01-01	17.936300000000000
1971-01-01	18.493000000000000
1972-01-01	18.379500000000000
1973-01-01	22.726500000000000
1974-01-01	24.994300000000000
1975-01-01	24.046800000000000
1976-01-01	23.903900000000000
1977-01-01	26.372000000000000
1978-01-01	32.006500000000000
1979-01-01	35.249000000000000
1980-01-01	34.268000000000000
1981-01-01	33.677600000000000
1982-01-01	33.770300000000000
1983-01-01	34.042800000000000
1984-01-01	31.428400000000000
1985-01-01	29.545100000000000
1986-01-01	27.300000000000000
1987-01-01	25.460700000000000
1988-01-01	27.855900000000000
1989-01-01	27.956999999999997
1990-01-01	27.570999999999998
1991-01-01	25.391200000000000
1992-01-01	25.671700000000000
1993-01-01	26.099300000000000
1994-01-01	20.744600000000000
1995-01-01	14.556000000000000
1996-01-01	14.677900000000000
1997-01-01	15.312800000000000
1998-01-01	14.558500000000000
1999-01-01	14.516700000000000
2000-01-01	16.491000000000000
2001-01-01	17.794400000000000
2002-01-01	17.896600000000000
2003-01-01	18.323800000000000
2004-01-01	19.300900000000000
2005-01-01	20.929300000000000
2006-01-01	22.116100000000000
2007-01-01	21.639400000000000
2008-01-01	22.480700000000000
2009-01-01	23.849500000000000
2010-01-01	24.354100000000000
2011-01-01	26.339800000000000
2012-01-01	27.921100000000000
2013-01-01	30.790700000000000
2014-01-01	32.444200000000000
2015-01-01	32.425300000000000
2016-01-01	31.786100000000000