Year	Percent
1981-01-01	4.0666699999999990
1982-01-01	4.5416700000000000
1983-01-01	5.0666699999999990
1984-01-01	5.4333300000000010
1985-01-01	5.0708300000000000
1986-01-01	4.7791700000000000
1987-01-01	5.1416699999999995
1988-01-01	5.1791700000000000
1989-01-01	5.1333300000000000
1990-01-01	5.1333300000000000
1991-01-01	5.8833300000000000
1992-01-01	6.8583300000000005
1993-01-01	4.5250000000000000
1994-01-01	4.7666699999999995
1995-01-01	4.8916699999999995
1996-01-01	4.8000000000000000
1997-01-01	5.2583300000000000
1998-01-01	5.5458300000000005
1999-01-01	4.9958300000000010
2000-01-01	5.2150000000000000
2001-01-01	5.5441699999999990
2002-01-01	5.7958300000000005
2003-01-01	5.9366699999999994
2004-01-01	5.7983300000000000
2005-01-01	5.9866699999999990
2006-01-01	5.6941700000000000
2007-01-01	5.6241699999999994
2008-01-01	5.5733300000000000
2009-01-01	6.3383300000000000
2010-01-01	6.0341700000000000
2011-01-01	6.0233300000000005
2012-01-01	6.1375000000000000
2013-01-01	6.1891700000000000
2014-01-01	5.8741699999999994
2015-01-01	6.7358300000000000
2016-01-01	7.7025000000000000