Year	Percent
1979-01-01	76.9949462083333
1980-01-01	78.0847201833333
1981-01-01	78.7159374916667
1982-01-01	78.0404756416667
1983-01-01	76.6238705083334
1984-01-01	75.7770719083333
1985-01-01	75.5810283583334
1986-01-01	75.9367816833334
1987-01-01	74.8265671750000
1988-01-01	74.6579202333334
1989-01-01	75.4007452500000
1990-01-01	75.2731253750000
1991-01-01	72.5545537250000
1992-01-01	72.2122827833334
1993-01-01	71.6493608000000
1994-01-01	72.9413571666666
1995-01-01	73.6645873916666
1996-01-01	73.7837048750000
1997-01-01	72.5285103000000
1998-01-01	72.0692678750000
1999-01-01	71.8285678583334
2000-01-01	71.8637821166667
2001-01-01	72.2348900333333
2002-01-01	71.6805236166667
2003-01-01	71.4029456083334
2004-01-01	71.1760926333333
2005-01-01	72.0168892916667
2006-01-01	72.0724570833333
2007-01-01	71.7909447833333
2008-01-01	71.9754241333333
2009-01-01	70.4140838833333
2010-01-01	69.6079519333333
2011-01-01	68.7898216333333
2012-01-01	68.2308023833333
2013-01-01	67.3688712500000
2014-01-01	66.8913785000000
2015-01-01	67.8225206000000
2016-01-01	67.1995511416667
2017-01-01	67.3878936416667