Year	Percent
1960-01-01	17.400000000000000
1961-01-01	16.750000000000000
1962-01-01	16.650000000000000
1963-01-01	10.425000000000000
1964-01-01	10.033300000000000
1965-01-01	10.137500000000000
1966-01-01	10.580000000000000
1967-01-01	13.666700000000000
1968-01-01	17.442900000000000
1969-01-01	19.950000000000000
1970-01-01	15.426300000000000
1971-01-01	11.005300000000000
1972-01-01	11.285100000000000
1973-01-01	12.587100000000000
1974-01-01	15.529000000000002
1975-01-01	10.206000000000000
1976-01-01	8.710200000000000
1977-01-01	12.476200000000000
1978-01-01	14.447500000000000
1979-01-01	15.630700000000000
1980-01-01	16.719700000000000
1981-01-01	16.365000000000000
1982-01-01	11.893600000000000
1983-01-01	9.687350000000000
1984-01-01	9.590050000000000
1985-01-01	7.614560000000001
1986-01-01	10.734600000000000
1987-01-01	11.681300000000000
1988-01-01	11.832000000000000
1989-01-01	7.097739999999999
1990-01-01	4.130750000000000
1991-01-01	5.021470000000000
1992-01-01	7.655050000000000
1993-01-01	11.587800000000000
1994-01-01	14.068000000000000
1995-01-01	14.966700000000000
1996-01-01	15.495100000000000
1997-01-01	18.087600000000000
1998-01-01	21.124700000000000
1999-01-01	24.082300000000000
2000-01-01	24.959600000000000
2001-01-01	24.397200000000000
2002-01-01	19.994000000000000
2003-01-01	19.364000000000000
2004-01-01	19.631900000000000
2005-01-01	19.504400000000000
2006-01-01	18.923900000000000
2007-01-01	18.453400000000000
2008-01-01	16.535800000000000
2009-01-01	17.131200000000000
2010-01-01	16.225100000000000
2011-01-01	15.800000000000000
2012-01-01	16.817400000000000
2013-01-01	17.320000000000000
2014-01-01	16.591800000000000
2015-01-01	17.850400000000000
2016-01-01	18.820700000000000