Year	Percent
1964-01-01	12.198600000000000
1965-01-01	12.280200000000000
1966-01-01	15.044200000000000
1967-01-01	19.294500000000000
1968-01-01	26.256700000000000
1969-01-01	26.256700000000000
1970-01-01	26.256700000000000
1971-01-01	26.256700000000000
1972-01-01	26.256700000000000
1973-01-01	23.359400000000000
1974-01-01	24.267000000000000
1975-01-01	26.526300000000000
1976-01-01	29.790800000000000
1977-01-01	31.415000000000000
1978-01-01	35.743400000000000
1979-01-01	32.334000000000000
1980-01-01	30.052900000000000
1981-01-01	32.006400000000000
1982-01-01	39.307600000000000
1983-01-01	44.074300000000000
1984-01-01	45.475600000000000
1985-01-01	48.038200000000000
1986-01-01	50.437500000000000
1987-01-01	51.478100000000000
1988-01-01	53.924800000000000
1989-01-01	49.306600000000000
1990-01-01	40.877200000000000
1991-01-01	30.342400000000000
1992-01-01	27.900900000000000
1993-01-01	28.755500000000000
1994-01-01	28.891900000000000
1995-01-01	24.023800000000000
1996-01-01	21.069500000000000
1997-01-01	21.719800000000000
1998-01-01	25.667600000000000
1999-01-01	26.467100000000000
2000-01-01	24.006800000000000
2001-01-01	32.459300000000000
2002-01-01	40.673800000000000
2003-01-01	41.640600000000000
2004-01-01	40.279500000000000
2005-01-01	35.862200000000000
2006-01-01	36.773600000000000
2007-01-01	40.896300000000000
2008-01-01	41.892400000000000
2009-01-01	49.222800000000000
2010-01-01	42.640500000000000
2011-01-01	40.144500000000000
2012-01-01	40.865300000000000
2013-01-01	41.983000000000004
2014-01-01	45.708400000000000
2015-01-01	50.562300000000000
2016-01-01	47.788999999999994