Year	Percent
1960-01-01	30.395700000000000
1961-01-01	42.394900000000000
1962-01-01	51.435300000000000
1963-01-01	54.239400000000000
1964-01-01	57.142800000000000
1965-01-01	58.983999999999995
1966-01-01	62.382000000000000
1967-01-01	72.100300000000000
1968-01-01	82.648800000000000
1969-01-01	88.554200000000000
1970-01-01	91.034800000000000
1971-01-01	92.962500000000000
1972-01-01	89.980500000000000
1973-01-01	87.670500000000000
1974-01-01	87.589300000000000
1975-01-01	84.320500000000000
1976-01-01	82.612500000000000
1977-01-01	83.484300000000000
1978-01-01	84.833900000000000
1979-01-01	87.649400000000000
1980-01-01	90.761500000000000
1981-01-01	91.570500000000000
1982-01-01	91.569600000000000
1983-01-01	91.956000000000000
1984-01-01	92.523900000000000
1985-01-01	93.537700000000000
1986-01-01	94.384700000000000
1987-01-01	94.969500000000000
1988-01-01	95.072900000000000
1989-01-01	95.523400000000000
1990-01-01	96.670100000000000
1991-01-01	97.386100000000000
1992-01-01	97.696400000000000
1993-01-01	97.891500000000000
1994-01-01	98.090200000000000
1995-01-01	98.539500000000000
1996-01-01	98.883300000000000
1997-01-01	98.141600000000000
1998-01-01	96.592900000000000
1999-01-01	96.935000000000000
2000-01-01	98.218700000000000
2001-01-01	98.550900000000000
2002-01-01	98.750700000000000
2003-01-01	98.931700000000000
2004-01-01	99.181300000000000
2005-01-01	99.244500000000000
2006-01-01	99.009100000000000
2007-01-01	98.834500000000000
2008-01-01	98.799400000000000
2009-01-01	98.805600000000000
2010-01-01	98.751200000000000
2011-01-01	98.768100000000000
2012-01-01	98.615400000000000
2013-01-01	98.770300000000000
2014-01-01	98.983600000000000
2015-01-01	99.073500000000000
2016-01-01	99.241400000000000