Year	Percent
1960-01-01	68.51770000000000
1961-01-01	62.00040000000000
1962-01-01	54.10330000000000
1963-01-01	48.14470000000000
1964-01-01	45.28120000000000
1965-01-01	49.84470000000000
1966-01-01	55.53650000000000
1967-01-01	55.32740000000000
1968-01-01	57.22770000000000
1969-01-01	62.84650000000000
1970-01-01	66.06840000000000
1971-01-01	68.41000000000000
1972-01-01	68.80990000000000
1973-01-01	70.60560000000000
1974-01-01	75.02990000000000
1975-01-01	78.45040000000000
1976-01-01	81.28230000000000
1977-01-01	84.81680000000000
1978-01-01	86.78390000000000
1979-01-01	88.22940000000000
1980-01-01	88.93170000000000
1981-01-01	89.07750000000000
1982-01-01	89.87750000000000
1983-01-01	85.81350000000000
1984-01-01	80.36010000000000
1985-01-01	77.24660000000000
1986-01-01	75.49570000000000
1987-01-01	73.67970000000000
1988-01-01	75.19320000000000
1989-01-01	73.77940000000000
1990-01-01	71.58990000000000
1991-01-01	79.57570000000000
1992-01-01	74.50000000000000
1993-01-01	69.17350000000000
1994-01-01	73.57310000000000
1995-01-01	76.37100000000001
1996-01-01	78.09010000000000
1997-01-01	75.88620000000000
1998-01-01	75.36730000000000
1999-01-01	77.20870000000000
2000-01-01	76.81730000000000
2001-01-01	76.50180000000000
2002-01-01	72.74080000000000
2003-01-01	71.31180000000000
2004-01-01	73.14720000000000
2005-01-01	73.85760000000000
2006-01-01	76.44360000000000
2007-01-01	80.86770000000000
2008-01-01	84.84890000000000
2009-01-01	88.49860000000000
2010-01-01	91.32950000000000
2011-01-01	92.87640000000000
2012-01-01	92.82980000000000
2013-01-01	96.16910000000000
2014-01-01	99.67960000000000
2015-01-01	99.74380000000000
2016-01-01	99.76160000000000