Year	Percent
1966-01-01	22.905000000000000
1967-01-01	22.947800000000000
1968-01-01	22.878400000000000
1969-01-01	24.078700000000000
1970-01-01	19.702500000000000
1971-01-01	20.545000000000000
1972-01-01	18.593300000000000
1973-01-01	19.120800000000000
1974-01-01	18.294100000000000
1975-01-01	17.039800000000000
1976-01-01	17.735500000000000
1977-01-01	19.420900000000000
1978-01-01	22.909500000000000
1979-01-01	22.931300000000000
1980-01-01	21.734500000000000
1981-01-01	19.400500000000000
1982-01-01	19.891400000000000
1983-01-01	19.508900000000000
1984-01-01	18.892000000000000
1985-01-01	18.640800000000000
1986-01-01	18.188800000000000
1987-01-01	20.051000000000000
1988-01-01	19.773300000000000
1989-01-01	19.015700000000000
1990-01-01	19.096300000000000
1991-01-01	20.376600000000000
1992-01-01	23.475600000000000
1993-01-01	25.493200000000000
1994-01-01	27.702400000000000
1995-01-01	28.612400000000000
1996-01-01	28.799200000000000
1997-01-01	31.653100000000000
1998-01-01	32.327500000000000
1999-01-01	31.951600000000000
2000-01-01	31.346100000000000
2001-01-01	30.857100000000000
2002-01-01	32.353700000000000
2003-01-01	33.766300000000000
2004-01-01	33.728400000000000
2005-01-01	33.487400000000000
2006-01-01	33.210100000000000
2007-01-01	32.926300000000000
2008-01-01	35.655500000000000
2009-01-01	33.905100000000000
2010-01-01	36.304600000000000
2011-01-01	38.017100000000000
2012-01-01	38.364000000000004
2013-01-01	39.748900000000000
2014-01-01	40.570500000000000
2015-01-01	40.162100000000000
2016-01-01	37.882200000000000