Year	Percent
1967-01-01	87.329600000000000
1968-01-01	86.790900000000000
1969-01-01	87.881900000000000
1970-01-01	92.126800000000000
1971-01-01	94.899400000000000
1972-01-01	93.580000000000000
1973-01-01	85.785900000000000
1974-01-01	84.707900000000000
1975-01-01	84.041400000000000
1976-01-01	79.279900000000000
1977-01-01	81.293000000000000
1978-01-01	86.167800000000000
1979-01-01	91.545800000000000
1980-01-01	95.515100000000000
1981-01-01	96.756000000000000
1982-01-01	98.964500000000000
1983-01-01	94.878999999999990
1984-01-01	80.171200000000000
1985-01-01	66.672900000000000
1986-01-01	56.016200000000000
1987-01-01	50.129400000000000
1988-01-01	48.924900000000000
1989-01-01	49.459100000000000
1990-01-01	52.106300000000000
1991-01-01	53.693100000000000
1992-01-01	55.653200000000000
1993-01-01	55.757300000000000
1994-01-01	45.932100000000000
1995-01-01	38.876900000000000
1996-01-01	50.536300000000000
1997-01-01	61.872900000000000
1998-01-01	63.492800000000000
1999-01-01	63.834800000000000
2000-01-01	50.862400000000000
2001-01-01	38.298600000000000
2002-01-01	41.282400000000000
2003-01-01	43.435500000000000
2004-01-01	45.406000000000006
2005-01-01	48.314800000000000
2006-01-01	52.220700000000000
2007-01-01	53.648700000000000
2008-01-01	60.046300000000000
2009-01-01	62.896400000000000
2010-01-01	61.159000000000000
2011-01-01	60.537800000000000
2012-01-01	58.318300000000000
2013-01-01	57.798700000000000
2014-01-01	59.265100000000000
2015-01-01	61.012700000000000
2016-01-01	55.973000000000000