Year	Percent
1960-01-01	13.837500000000000
1961-01-01	14.479600000000000
1962-01-01	15.815300000000000
1963-01-01	15.566700000000000
1964-01-01	14.032800000000000
1965-01-01	13.805000000000000
1966-01-01	13.447000000000001
1967-01-01	13.881700000000000
1968-01-01	14.265400000000000
1969-01-01	14.727000000000000
1970-01-01	10.171700000000000
1971-01-01	9.907890000000000
1972-01-01	9.565489999999999
1973-01-01	10.148800000000000
1974-01-01	10.950300000000000
1975-01-01	12.681100000000000
1976-01-01	13.694000000000000
1977-01-01	14.202000000000000
1978-01-01	13.734700000000000
1979-01-01	13.257900000000000
1980-01-01	13.832600000000000
1981-01-01	16.420200000000000
1982-01-01	17.299500000000000
1983-01-01	17.891000000000000
1984-01-01	17.624800000000000
1985-01-01	17.875300000000000
1986-01-01	17.875300000000000
1987-01-01	14.453900000000000
1988-01-01	13.048200000000000
1989-01-01	13.048200000000000
1990-01-01	15.713700000000000
1991-01-01	16.322800000000000
1992-01-01	17.538000000000000
1993-01-01	18.594600000000000
1994-01-01	20.445000000000000
1995-01-01	22.451900000000000
1996-01-01	23.595100000000000
1997-01-01	23.732300000000000
1998-01-01	24.422700000000000
1999-01-01	24.547800000000000
2000-01-01	22.696100000000000
2001-01-01	17.314800000000000
2002-01-01	12.998600000000000
2003-01-01	13.264100000000000
2004-01-01	13.669500000000000
2005-01-01	15.129800000000000
2006-01-01	16.147300000000000
2007-01-01	16.667900000000000
2008-01-01	16.538000000000000
2009-01-01	17.230200000000000
2010-01-01	18.335100000000000
2011-01-01	19.170800000000000
2012-01-01	20.830700000000000
2013-01-01	22.544900000000000
2014-01-01	23.688500000000000
2015-01-01	24.279500000000000
2016-01-01	23.597700000000000