Year	Percent
1980-01-01	19.473800000000000
1981-01-01	19.735100000000000
1982-01-01	21.261800000000000
1983-01-01	23.217600000000000
1984-01-01	29.338100000000000
1985-01-01	23.270700000000000
1986-01-01	31.849800000000000
1987-01-01	35.898900000000000
1988-01-01	34.782100000000000
1989-01-01	33.461100000000000
1990-01-01	31.922500000000000
1991-01-01	31.358500000000000
1992-01-01	29.996600000000000
1993-01-01	30.686000000000000
1994-01-01	34.652000000000000
1995-01-01	34.673900000000000
1996-01-01	33.236100000000000
1997-01-01	31.028300000000000
1998-01-01	31.028300000000000
1999-01-01	25.017000000000000
2000-01-01	23.270000000000000
2001-01-01	19.825000000000000
2002-01-01	18.455400000000000
2003-01-01	17.243800000000000
2004-01-01	17.243800000000000
2005-01-01	15.168700000000000
2006-01-01	13.693700000000000
2007-01-01	11.731500000000000
2008-01-01	11.256700000000000
2009-01-01	13.879800000000000
2010-01-01	15.030300000000000
2011-01-01	15.312700000000000
2012-01-01	16.292600000000000
2013-01-01	16.019000000000002
2014-01-01	18.839100000000000
2015-01-01	17.885700000000000
2016-01-01	17.236200000000000