Year	Percent
1960-01-01	8.777880000000000
1961-01-01	8.959560000000000
1962-01-01	10.640600000000000
1963-01-01	12.819500000000000
1964-01-01	14.961500000000000
1965-01-01	17.363000000000000
1966-01-01	18.927500000000000
1967-01-01	21.477300000000000
1968-01-01	21.036200000000000
1969-01-01	20.828600000000000
1970-01-01	19.131000000000000
1971-01-01	19.438200000000000
1972-01-01	20.800000000000000
1973-01-01	18.900000000000000
1974-01-01	14.880300000000000
1975-01-01	13.292700000000000
1976-01-01	14.405500000000000
1977-01-01	16.110700000000000
1978-01-01	16.163300000000000
1979-01-01	16.233300000000000
1980-01-01	15.855100000000000
1981-01-01	15.370999999999999
1982-01-01	15.569300000000000
1983-01-01	16.651000000000000
1984-01-01	17.208300000000000
1985-01-01	19.097800000000000
1986-01-01	21.162500000000000
1987-01-01	20.858500000000000
1988-01-01	19.261900000000000
1989-01-01	18.582600000000000
1990-01-01	17.797900000000000
1991-01-01	16.367400000000000
1992-01-01	16.306900000000000
1993-01-01	17.588000000000000
1994-01-01	17.169600000000000
1995-01-01	16.884900000000000
1996-01-01	17.489000000000000
1997-01-01	17.842200000000000
1998-01-01	18.166900000000000
1999-01-01	18.425200000000000
2000-01-01	19.456800000000000
2001-01-01	19.511500000000000
2002-01-01	19.730400000000000
2003-01-01	20.383500000000000
2004-01-01	23.136100000000000
2005-01-01	25.121500000000000
2006-01-01	24.779200000000000
2007-01-01	25.551200000000000
2008-01-01	27.098500000000000
2009-01-01	22.980999999999998
2010-01-01	20.982200000000000
2011-01-01	17.837800000000000
2012-01-01	16.927300000000000
2013-01-01	15.681400000000000
2014-01-01	15.056300000000000
2015-01-01	14.771700000000000
2016-01-01	15.470400000000000