Year	Percent
1980-01-01	20.888800000000000
1981-01-01	22.856700000000000
1982-01-01	24.317300000000000
1983-01-01	24.389500000000000
1984-01-01	24.285800000000000
1985-01-01	24.287200000000000
1986-01-01	23.280800000000000
1987-01-01	24.061900000000000
1988-01-01	24.742300000000000
1989-01-01	23.452700000000000
1990-01-01	23.790600000000000
1991-01-01	21.162000000000000
1992-01-01	23.171200000000000
1993-01-01	25.629400000000000
1994-01-01	26.913100000000000
1995-01-01	29.837200000000000
1996-01-01	31.650600000000000
1997-01-01	32.663100000000000
1998-01-01	32.566100000000000
1999-01-01	31.670000000000000
2000-01-01	30.124000000000002
2001-01-01	26.965600000000000
2002-01-01	26.542200000000000
2003-01-01	26.379500000000000
2004-01-01	26.589900000000000
2005-01-01	25.236900000000000
2006-01-01	22.959700000000000
2007-01-01	20.124500000000000
2008-01-01	18.586200000000000
2009-01-01	20.121200000000000
2010-01-01	24.565000000000000
2011-01-01	20.755900000000000
2012-01-01	21.535000000000000
2013-01-01	20.727500000000000
2014-01-01	19.711000000000000
2015-01-01	18.885600000000000
2016-01-01	17.134800000000000