Year	Percent
1971-01-01	18.276800000000000
1972-01-01	19.018600000000000
1973-01-01	24.374400000000000
1974-01-01	26.617200000000000
1975-01-01	22.359600000000000
1976-01-01	18.775400000000000
1977-01-01	20.988500000000000
1978-01-01	22.452200000000000
1979-01-01	18.873000000000000
1980-01-01	17.298000000000000
1981-01-01	17.411600000000000
1982-01-01	16.569200000000000
1983-01-01	15.962600000000000
1984-01-01	14.105500000000000
1985-01-01	11.161900000000000
1986-01-01	9.579780000000000
1987-01-01	8.606689999999999
1988-01-01	8.509830000000001
1989-01-01	8.947569999999999
1990-01-01	9.363700000000000
1991-01-01	9.922160000000000
1992-01-01	10.210100000000000
1993-01-01	10.448600000000000
1994-01-01	12.440600000000000
1995-01-01	15.144500000000000
1996-01-01	17.016100000000000
1997-01-01	17.749900000000000
1998-01-01	18.538900000000000
1999-01-01	19.772000000000002
2000-01-01	20.591200000000000
2001-01-01	23.218400000000000
2002-01-01	25.148100000000000
2003-01-01	29.989400000000000
2004-01-01	29.488500000000000
2005-01-01	30.121600000000000
2006-01-01	28.139000000000000
2007-01-01	24.993600000000000
2008-01-01	25.973200000000000
2009-01-01	24.717900000000000
2010-01-01	25.006999999999998
2011-01-01	26.256999999999998
2012-01-01	24.277700000000000
2013-01-01	23.205600000000000
2014-01-01	24.931100000000000
2015-01-01	27.658400000000000
2016-01-01	29.065900000000000