Year	Percent
1979-01-01	74.3919973166666
1980-01-01	74.3691096250000
1981-01-01	74.2962448166666
1982-01-01	72.5166288916667
1983-01-01	69.2604404666667
1984-01-01	69.6299629083334
1985-01-01	69.7374573416667
1986-01-01	70.0433313000000
1987-01-01	69.4941522916667
1988-01-01	70.1437668250000
1989-01-01	71.1359052666667
1990-01-01	70.5022004333333
1991-01-01	67.2659054750000
1992-01-01	65.7515182750000
1993-01-01	65.0811987500000
1994-01-01	66.2585133000000
1995-01-01	67.3550211500000
1996-01-01	67.1699289750000
1997-01-01	66.7367891083333
1998-01-01	66.9248369750000
1999-01-01	67.1558464416667
2000-01-01	67.4394657250000
2001-01-01	66.8476955750000
2002-01-01	67.1001837166667
2003-01-01	67.3275166083333
2004-01-01	67.7339130916667
2005-01-01	68.5691002166667
2006-01-01	68.8638489250000
2007-01-01	69.5790905416666
2008-01-01	69.7478781083333
2009-01-01	68.1873668166667
2010-01-01	68.6873184666667
2011-01-01	68.6406422583333
2012-01-01	68.0417575166667
2013-01-01	67.3172614916667
2014-01-01	66.7009483416667
2015-01-01	66.8010280000000
2016-01-01	66.6178834250000
2017-01-01	66.7762130583334