Year	Percent
1960-01-01	68.359800000000000
1961-01-01	76.615200000000000
1962-01-01	85.544600000000000
1963-01-01	86.917800000000000
1964-01-01	86.143800000000000
1965-01-01	81.543400000000000
1966-01-01	80.021300000000000
1967-01-01	80.771700000000000
1968-01-01	83.317400000000000
1969-01-01	81.143800000000000
1970-01-01	73.253900000000000
1971-01-01	69.675600000000000
1972-01-01	68.858500000000000
1973-01-01	68.731400000000000
1974-01-01	70.238900000000000
1975-01-01	69.560300000000000
1976-01-01	70.130600000000000
1977-01-01	71.163300000000000
1978-01-01	67.080000000000000
1979-01-01	63.654500000000000
1980-01-01	62.936500000000000
1981-01-01	62.529200000000000
1982-01-01	65.594100000000000
1983-01-01	65.806400000000000
1984-01-01	64.201600000000000
1985-01-01	62.665400000000000
1986-01-01	62.665400000000000
1987-01-01	62.665400000000000
1988-01-01	62.665400000000000
1989-01-01	62.665400000000000
1990-01-01	46.912500000000000
1991-01-01	48.294700000000000
1992-01-01	53.810600000000000
1993-01-01	55.111000000000004
1994-01-01	55.819800000000000
1995-01-01	58.441700000000000
1996-01-01	62.080700000000000
1997-01-01	74.896400000000000
1998-01-01	85.668300000000000
1999-01-01	87.310800000000000
2000-01-01	86.465100000000000
2001-01-01	81.842700000000000
2002-01-01	77.178600000000000
2003-01-01	75.407300000000000
2004-01-01	74.473800000000000
2005-01-01	73.770300000000000
2006-01-01	73.624100000000000
2007-01-01	77.624100000000000
2008-01-01	85.100100000000000
2009-01-01	91.310500000000000
2010-01-01	84.880100000000000
2011-01-01	78.563100000000000
2012-01-01	80.595900000000000
2013-01-01	79.889400000000000
2014-01-01	77.330900000000000
2015-01-01	73.792700000000000
2016-01-01	71.277900000000000