Year	Percent
1973-01-01	13.224900000000000
1974-01-01	15.677800000000000
1975-01-01	17.998500000000000
1976-01-01	17.654200000000000
1977-01-01	17.206300000000000
1978-01-01	18.596000000000000
1979-01-01	20.586300000000000
1980-01-01	22.560800000000000
1981-01-01	22.938400000000000
1982-01-01	24.022400000000000
1983-01-01	22.500700000000000
1984-01-01	20.538400000000000
1985-01-01	17.555999999999997
1986-01-01	13.654500000000000
1987-01-01	14.684200000000000
1988-01-01	12.645300000000000
1989-01-01	15.978200000000000
1990-01-01	21.327100000000000
1991-01-01	21.618900000000000
1992-01-01	20.018100000000000
1993-01-01	21.208800000000000
1994-01-01	21.050000000000000
1995-01-01	17.598700000000000
1996-01-01	13.831400000000000
1997-01-01	10.869600000000000
1998-01-01	8.031450000000000
1999-01-01	7.004600000000000
2000-01-01	7.019920000000000
2001-01-01	7.320060000000001
2002-01-01	8.286870000000000
2003-01-01	9.275610000000000
2004-01-01	9.873550000000000
2005-01-01	11.800100000000000
2006-01-01	13.008700000000000
2007-01-01	15.065500000000000
2008-01-01	16.057500000000000
2009-01-01	16.423700000000000
2010-01-01	16.606600000000000
2011-01-01	16.611700000000000
2012-01-01	17.175800000000000
2013-01-01	17.924000000000000
2014-01-01	18.848600000000000
2015-01-01	19.296700000000000
2016-01-01	18.846900000000000