Year	Percent
1960-01-01	73.61960000000000
1961-01-01	69.90370000000000
1962-01-01	67.73750000000000
1963-01-01	62.71940000000000
1964-01-01	60.36210000000000
1965-01-01	62.38980000000000
1966-01-01	63.36720000000000
1967-01-01	59.17920000000000
1968-01-01	56.70080000000000
1969-01-01	60.61240000000000
1970-01-01	62.05100000000000
1971-01-01	69.45450000000000
1972-01-01	75.11810000000000
1973-01-01	76.91980000000000
1974-01-01	78.61680000000000
1975-01-01	80.62840000000000
1976-01-01	82.75690000000000
1977-01-01	84.18320000000000
1978-01-01	85.05330000000000
1979-01-01	85.25260000000000
1980-01-01	83.98720000000000
1981-01-01	82.06790000000000
1982-01-01	80.14330000000000
1983-01-01	77.37560000000000
1984-01-01	76.06380000000000
1985-01-01	78.25510000000000
1986-01-01	83.05330000000000
1987-01-01	85.38090000000000
1988-01-01	86.52940000000000
1989-01-01	89.29050000000000
1990-01-01	91.22350000000000
1991-01-01	88.93910000000000
1992-01-01	88.34010000000000
1993-01-01	91.85700000000001
1994-01-01	92.32700000000001
1995-01-01	93.11540000000000
1996-01-01	94.82010000000000
1997-01-01	94.98980000000000
1998-01-01	95.44270000000000
1999-01-01	95.42110000000000
2000-01-01	95.01410000000000
2001-01-01	94.70260000000000
2002-01-01	94.94480000000000
2003-01-01	90.22530000000000
2004-01-01	79.77710000000000
2005-01-01	68.09890000000000
2006-01-01	58.39120000000000
2007-01-01	55.33320000000000
2008-01-01	57.15310000000000
2009-01-01	59.27180000000000
2010-01-01	61.32310000000000
2011-01-01	62.50740000000000
2012-01-01	63.38500000000000
2013-01-01	64.65270000000000
2014-01-01	65.74720000000000
2015-01-01	66.66070000000000
2016-01-01	67.33870000000000