Year	Percent
1980-01-01	4.5000000000000000
1981-01-01	4.0000000000000000
1982-01-01	4.5000000000000000
1983-01-01	4.0833300000000000
1984-01-01	4.9583300000000000
1985-01-01	4.5416700000000000
1986-01-01	4.7500000000000000
1987-01-01	5.0000000000000000
1988-01-01	5.0000000000000000
1989-01-01	5.7916700000000000
1990-01-01	5.5000000000000000
1991-01-01	7.6959700000000000
1992-01-01	8.1807600000000010
1993-01-01	8.1609400000000000
1994-01-01	7.0195700000000000
1995-01-01	7.3086300000000000
1996-01-01	7.2420700000000000
1997-01-01	6.7214500000000000
1998-01-01	7.0208400000000000
1999-01-01	7.9461600000000010
2000-01-01	7.6244600000000010
2001-01-01	6.9539700000000000
2002-01-01	7.4040000000000000
2003-01-01	8.1701800000000000
2004-01-01	6.6266700000000000
2005-01-01	6.5854300000000010
2006-01-01	5.7769800000000000
2007-01-01	5.9300000000000000
2008-01-01	5.6262500000000000
2009-01-01	6.7373400000000000
2010-01-01	5.6731200000000000
2011-01-01	5.6476200000000000
2012-01-01	6.0640000000000000
2013-01-01	6.0126599999999994
2014-01-01	5.9760000000000000
2015-01-01	6.3600000000000000
2016-01-01	6.4300000000000000