Year	Percent
1980-01-01	5.32500
1981-01-01	4.60000
1982-01-01	4.60000
1983-01-01	4.60000
1984-01-01	4.60000
1985-01-01	4.60000
1986-01-01	3.40000
1987-01-01	4.40000
1988-01-01	6.10000
1989-01-01	6.00000
1990-01-01	6.00000
1991-01-01	6.00000
1992-01-01	6.30000
1993-01-01	6.30000
1994-01-01	6.30000
1995-01-01	6.30000
1996-01-01	7.60000
1997-01-01	7.37000
1998-01-01	8.01000
1999-01-01	8.23000
2000-01-01	8.55000
2001-01-01	9.26000
2002-01-01	7.98000
2003-01-01	6.98000
2004-01-01	6.44000
2005-01-01	6.48000
2006-01-01	6.02000
2007-01-01	5.92000
2008-01-01	5.59000
2009-01-01	5.81000
2010-01-01	6.36000
2011-01-01	7.65000
2012-01-01	8.04000
2013-01-01	7.77000
2014-01-01	8.46000
2015-01-01	7.58620
2016-01-01	7.45777