Year	Percent
1973-01-01	13.332900000000000
1974-01-01	16.375999999999998
1975-01-01	11.767200000000000
1976-01-01	8.648719999999999
1977-01-01	11.295800000000000
1978-01-01	13.671800000000000
1979-01-01	16.003100000000000
1980-01-01	18.045800000000000
1981-01-01	23.862500000000000
1982-01-01	25.375700000000000
1983-01-01	19.323700000000000
1984-01-01	16.453000000000000
1985-01-01	12.090700000000000
1986-01-01	15.054000000000000
1987-01-01	16.897200000000000
1988-01-01	14.921900000000000
1989-01-01	32.073900000000000
1990-01-01	12.800100000000000
1991-01-01	12.565500000000000
1992-01-01	15.633900000000000
1993-01-01	19.248300000000000
1994-01-01	20.908200000000000
1995-01-01	22.993300000000000
1996-01-01	23.499700000000000
1997-01-01	24.558900000000000
1998-01-01	27.352900000000000
1999-01-01	30.896900000000000
2000-01-01	30.896300000000000
2001-01-01	30.523300000000000
2002-01-01	33.313100000000000
2003-01-01	33.893100000000000
2004-01-01	29.293200000000000
2005-01-01	26.669500000000000
2006-01-01	23.223400000000000
2007-01-01	20.472700000000000
2008-01-01	18.236600000000000
2009-01-01	19.493400000000000
2010-01-01	18.680900000000000
2011-01-01	18.624000000000002
2012-01-01	19.561700000000000
2013-01-01	19.559300000000000
2014-01-01	18.981400000000000
2015-01-01	20.150500000000000
2016-01-01	19.657000000000000