Year	Percent
1980-01-01	7.500000000000000
1981-01-01	8.000000000000000
1982-01-01	8.000000000000000
1983-01-01	9.000000000000000
1984-01-01	9.000000000000000
1985-01-01	7.791670000000000
1986-01-01	10.000000000000000
1987-01-01	11.750000000000000
1988-01-01	12.166700000000000
1989-01-01	14.000000000000000
1990-01-01	14.000000000000000
1991-01-01	14.000000000000000
1992-01-01	14.000000000000000
1993-01-01	14.000000000000000
1994-01-01	14.000000000000000
1995-01-01	18.208300000000000
1996-01-01	20.373300000000000
1997-01-01	18.436700000000000
1998-01-01	15.139200000000000
1999-01-01	14.144200000000000
2000-01-01	14.190800000000000
2001-01-01	15.246400000000000
2002-01-01	13.109200000000000
2003-01-01	11.469100000000000
2004-01-01	9.939650000000000
2005-01-01	10.516200000000000
2006-01-01	8.925580000000000
2007-01-01	7.390830000000000
2008-01-01	6.729480000000001
2009-01-01	7.058680000000001
2010-01-01	7.921280000000000
2011-01-01	8.185340000000000
2012-01-01	6.010790000000000
2013-01-01	5.893400000000000
2014-01-01	6.433910000000000
2015-01-01	6.207990000000001
2016-01-01	5.463640000000000