Year	Percent
1960-01-01	66.66670000000000
1961-01-01	68.44890000000000
1962-01-01	75.03830000000000
1963-01-01	78.70150000000000
1964-01-01	80.56820000000000
1965-01-01	85.70510000000000
1966-01-01	89.40520000000000
1967-01-01	83.81660000000000
1968-01-01	78.88910000000000
1969-01-01	73.27070000000000
1970-01-01	68.12899999999999
1971-01-01	65.58800000000001
1972-01-01	69.90190000000000
1973-01-01	78.46610000000000
1974-01-01	82.63799999999999
1975-01-01	85.17740000000000
1976-01-01	86.32580000000000
1977-01-01	85.10260000000000
1978-01-01	86.41080000000000
1979-01-01	89.51970000000000
1980-01-01	92.44360000000000
1981-01-01	92.19410000000000
1982-01-01	90.00310000000000
1983-01-01	86.18620000000000
1984-01-01	83.15160000000000
1985-01-01	83.28470000000000
1986-01-01	85.11850000000000
1987-01-01	87.99590000000000
1988-01-01	89.18890000000000
1989-01-01	89.83920000000000
1990-01-01	90.99900000000000
1991-01-01	92.13910000000000
1992-01-01	93.28250000000000
1993-01-01	94.26790000000000
1994-01-01	95.22030000000000
1995-01-01	95.80640000000000
1996-01-01	95.98050000000000
1997-01-01	96.18350000000000
1998-01-01	96.55570000000000
1999-01-01	96.91610000000000
2000-01-01	97.13170000000000
2001-01-01	97.37660000000000
2002-01-01	97.74060000000000
2003-01-01	98.00860000000000
2004-01-01	98.24130000000000
2005-01-01	98.64920000000000
2006-01-01	98.96730000000000
2007-01-01	98.84720000000000
2008-01-01	99.09730000000000
2009-01-01	98.46170000000000
2010-01-01	97.61000000000000
2011-01-01	97.87870000000000
2012-01-01	97.87430000000000
2013-01-01	97.93760000000000
2014-01-01	98.32600000000001
2015-01-01	98.70130000000000
2016-01-01	98.94400000000000