Year	Percent
1979-01-01	61.3287183250000
1980-01-01	63.1339034750000
1981-01-01	63.9180944666667
1982-01-01	61.8189772166667
1983-01-01	58.2422046250000
1984-01-01	59.1077682666667
1985-01-01	60.4235118083333
1986-01-01	61.1729711500000
1987-01-01	60.6483650500000
1988-01-01	61.5082161000000
1989-01-01	64.0514024666667
1990-01-01	62.7161580083333
1991-01-01	57.4763234250000
1992-01-01	56.0067171833333
1993-01-01	55.9820585666667
1994-01-01	58.6662804666667
1995-01-01	60.7491896750000
1996-01-01	60.4477820083333
1997-01-01	58.9533346666667
1998-01-01	59.7617336500000
1999-01-01	60.7495878583333
2000-01-01	61.6927935750000
2001-01-01	61.1434563500000
2002-01-01	61.0158984916667
2003-01-01	61.8183982500000
2004-01-01	62.1628471500000
2005-01-01	63.2884833000000
2006-01-01	63.6973640750000
2007-01-01	64.1325609666667
2008-01-01	64.5145221916667
2009-01-01	61.1826503833333
2010-01-01	60.5208044916667
2011-01-01	60.3902746583333
2012-01-01	59.6009900166667
2013-01-01	58.6615859833333
2014-01-01	57.7197278083333
2015-01-01	58.4655072333333
2016-01-01	58.3447411333333
2017-01-01	58.4459587833333