Year	Percent
1980-01-01	3.8758300000000000
1981-01-01	3.5225000000000000
1982-01-01	3.4425000000000000
1983-01-01	3.5325000000000000
1984-01-01	3.5600000000000000
1985-01-01	3.9350000000000000
1986-01-01	3.6800000000000000
1987-01-01	3.5000000000000000
1988-01-01	3.0300000000000000
1989-01-01	2.5166700000000000
1990-01-01	2.4291700000000000
1991-01-01	2.0833300000000000
1992-01-01	1.9500000000000000
1993-01-01	2.2683299999999997
1994-01-01	2.5741700000000000
1995-01-01	2.5533300000000000
1996-01-01	1.6141700000000000
1997-01-01	1.5216700000000000
1998-01-01	1.3875000000000000
1999-01-01	1.8025000000000000
2000-01-01	1.9208300000000000
2001-01-01	1.7541700000000000
2002-01-01	1.7483300000000000
2003-01-01	2.0508300000000000
2004-01-01	2.1750000000000000
2005-01-01	2.3183300000000000
2006-01-01	2.1416700000000000
2007-01-01	1.8091700000000002
2008-01-01	1.5791700000000000
2009-01-01	1.7175000000000000
2010-01-01	2.0591700000000000
2011-01-01	2.4288100000000000
2012-01-01	2.7379200000000000
2013-01-01	3.0700000000000000
2014-01-01	3.3325000000000000
2015-01-01	3.3450000000000000
2016-01-01	3.5083300000000004