Year	Percent
1964-01-01	18.136400000000000
1965-01-01	17.837400000000000
1966-01-01	17.928200000000000
1967-01-01	18.207100000000000
1968-01-01	24.495500000000000
1969-01-01	20.329800000000000
1970-01-01	12.544500000000000
1971-01-01	11.165400000000000
1972-01-01	8.935039999999999
1973-01-01	8.444289999999999
1974-01-01	9.519169999999999
1975-01-01	8.139900000000000
1976-01-01	7.662839999999999
1977-01-01	9.064060000000001
1978-01-01	12.610500000000000
1979-01-01	12.783000000000000
1980-01-01	14.316900000000000
1981-01-01	14.538900000000000
1982-01-01	14.077000000000000
1983-01-01	13.805300000000000
1984-01-01	17.052100000000000
1985-01-01	15.831900000000000
1986-01-01	14.722700000000000
1987-01-01	9.064620000000000
1988-01-01	8.384880000000000
1989-01-01	7.762160000000001
1990-01-01	7.359070000000000
1991-01-01	7.018170000000000
1992-01-01	6.028519999999999
1993-01-01	6.186360000000000
1994-01-01	7.389469999999999
1995-01-01	7.086310000000001
1996-01-01	6.087040000000000
1997-01-01	6.419690000000000
1998-01-01	7.039530000000000
1999-01-01	7.614950000000000
2000-01-01	8.005300000000000
2001-01-01	8.055900000000000
2002-01-01	9.565040000000000
2003-01-01	9.657090000000000
2004-01-01	8.897450000000000
2005-01-01	8.729010000000000
2006-01-01	10.530400000000000
2007-01-01	12.170400000000000
2008-01-01	13.199600000000000
2009-01-01	14.039300000000000
2010-01-01	14.749500000000000
2011-01-01	16.570000000000000
2012-01-01	15.470600000000000
2013-01-01	14.433900000000000
2014-01-01	13.304700000000000