Year	Percent
1980-01-01	3.7500000000000000
1981-01-01	3.7500000000000000
1982-01-01	3.7500000000000000
1983-01-01	3.7500000000000000
1984-01-01	3.7500000000000000
1985-01-01	3.7500000000000000
1986-01-01	3.7500000000000000
1987-01-01	3.7500000000000000
1988-01-01	3.7500000000000000
1989-01-01	5.3333300000000000
1990-01-01	6.2500000000000000
1991-01-01	6.2500000000000000
1992-01-01	8.0000000000000000
1993-01-01	5.6900000000000000
1994-01-01	5.7182900000000005
1995-01-01	5.7566400000000000
1996-01-01	5.3986400000000000
1997-01-01	5.5802700000000000
1998-01-01	5.6180500000000000
1999-01-01	5.9452000000000000
2000-01-01	5.9813700000000000
2001-01-01	5.8730900000000000
2002-01-01	5.9282500000000000
2003-01-01	5.8761300000000000
2004-01-01	5.7393500000000000
2005-01-01	5.4800600000000000
2006-01-01	5.3951699999999990
2007-01-01	5.3970000000000000
2008-01-01	5.9328800000000000
2009-01-01	7.2073000000000000
2010-01-01	7.5078200000000000
2011-01-01	7.4552700000000000
2012-01-01	6.8119000000000000
2013-01-01	6.5311100000000000
2014-01-01	5.8115400000000000
2015-01-01	5.2154700000000000
2016-01-01	4.7921300000000000