Year	Percent
1979-01-01	82.1067714166667
1980-01-01	82.2581297333333
1981-01-01	82.3239961583333
1982-01-01	80.5068128000000
1983-01-01	76.9261000166667
1984-01-01	77.4048171500000
1985-01-01	77.6591030916667
1986-01-01	78.2166625916666
1987-01-01	77.7288869083334
1988-01-01	78.5618439833333
1989-01-01	79.8052409083333
1990-01-01	79.2123318583333
1991-01-01	75.7557685333334
1992-01-01	74.1605051916666
1993-01-01	73.6997459083334
1994-01-01	75.0552903416667
1995-01-01	76.3848185583334
1996-01-01	76.3037018500000
1997-01-01	75.8458622500000
1998-01-01	76.1705924416666
1999-01-01	76.5988056750000
2000-01-01	76.9245406416667
2001-01-01	76.3579576000000
2002-01-01	76.6895701250000
2003-01-01	77.0550408583333
2004-01-01	77.6050873583333
2005-01-01	78.5057049666667
2006-01-01	78.8097965833333
2007-01-01	79.5439623583333
2008-01-01	79.6843005750000
2009-01-01	77.7897546000000
2010-01-01	78.5927521416667
2011-01-01	78.6739646583334
2012-01-01	78.1329600666667
2013-01-01	77.5424091250000
2014-01-01	77.0710029750000
2015-01-01	77.5371384916667
2016-01-01	77.5367226250000
2017-01-01	77.8893799750000