Year	Percent
1980-01-01	5.0000000000000000
1981-01-01	4.6666700000000000
1982-01-01	5.7083300000000000
1983-01-01	5.3333300000000000
1984-01-01	5.3333300000000000
1985-01-01	6.2433300000000000
1986-01-01	6.6925000000000000
1987-01-01	6.9800000000000000
1988-01-01	6.4083300000000000
1989-01-01	5.4208300000000005
1990-01-01	5.7591700000000000
1991-01-01	5.4175000000000000
1992-01-01	5.4275000000000000
1993-01-01	6.4558300000000010
1994-01-01	6.7150000000000000
1995-01-01	7.6158300000000000
1996-01-01	7.5833300000000000
1997-01-01	7.5000000000000000
1998-01-01	7.5833300000000000
1999-01-01	7.5575000000000000
2000-01-01	7.4700000000000000
2001-01-01	7.1000000000000000
2002-01-01	7.2333300000000005
2003-01-01	7.0366700000000000
2004-01-01	6.6608300000000010
2005-01-01	6.6125000000000000
2006-01-01	6.2366699999999990
2007-01-01	6.1125000000000000
2008-01-01	6.6666700000000000
2009-01-01	5.9716700000000000
2010-01-01	5.8966699999999990
2011-01-01	6.1500000000000000
2012-01-01	6.2850000000000000
2013-01-01	6.4200000000000000
2014-01-01	6.4850000000000000
2015-01-01	6.7716699999999990