Year	Percent
1981-01-01	3.0000000000000000
1982-01-01	3.0000000000000000
1983-01-01	2.5000000000000000
1984-01-01	3.5000000000000000
1985-01-01	5.0416700000000000
1986-01-01	5.5000000000000000
1987-01-01	5.4166700000000000
1988-01-01	4.0833300000000000
1989-01-01	4.5833300000000000
1990-01-01	4.5000000000000000
1991-01-01	6.9149699999999990
1992-01-01	5.9781699999999995
1993-01-01	6.6337199999999990
1994-01-01	6.8894699999999990
1995-01-01	6.3924800000000000
1996-01-01	6.8694300000000000
1997-01-01	7.1579000000000000
1998-01-01	7.0551300000000000
1999-01-01	6.8827600000000000
2000-01-01	6.7410700000000000
2001-01-01	6.9707200000000000
2002-01-01	6.6736400000000000
2003-01-01	7.6691500000000000
2004-01-01	5.6576100000000000
2005-01-01	5.4276700000000000
2006-01-01	4.8232800000000005
2007-01-01	4.3700000000000000
2008-01-01	4.1661300000000000
2009-01-01	4.0507200000000000
2010-01-01	4.0364100000000000
2011-01-01	4.9732400000000005
2012-01-01	4.4507300000000000
2013-01-01	5.5702700000000000
2014-01-01	6.2770000000000000
2015-01-01	6.6300000000000000
2016-01-01	6.7800000000000000