Year	Percent
1960-01-01	85.5429668991267
1961-01-01	84.3274869560297
1962-01-01	85.0213713399126
1963-01-01	84.5660168273746
1964-01-01	84.7065728800395
1965-01-01	84.9392568511769
1966-01-01	85.4507599983159
1967-01-01	85.5441641813292
1968-01-01	85.3002768052002
1969-01-01	85.0431095130454
1970-01-01	83.4305721417701
1971-01-01	82.0479832607220
1972-01-01	82.2451136024395
1973-01-01	82.9516616047895
1974-01-01	82.2895187721133
1975-01-01	78.8851889555674
1976-01-01	79.4420978715259
1977-01-01	80.3755206985234
1978-01-01	81.4413736920265
1979-01-01	81.6274026757288
1980-01-01	79.7343119227541
1981-01-01	79.0214262856226
1982-01-01	76.5896169097927
1983-01-01	76.4533612728294
1984-01-01	78.8082059193034
1985-01-01	79.2996641475178
1986-01-01	79.4305247066118
1987-01-01	80.0542338595734
1988-01-01	80.7393581766523
1989-01-01	81.3502305108489
1990-01-01	80.6793887219505
1991-01-01	78.9148002423716
1992-01-01	78.3419695881691
1993-01-01	78.6845378589145
1994-01-01	79.0288325455586
1995-01-01	79.5492387301049
1996-01-01	79.6750511361669
1997-01-01	80.0677286186607
1998-01-01	80.4750040167576
1999-01-01	80.4978263748333
2000-01-01	80.6337899410581
2001-01-01	79.3923092165229
2002-01-01	77.9693878344231
2003-01-01	76.9481375876525
2004-01-01	77.2249530047288
2005-01-01	77.6099445041714
2006-01-01	78.0951654043632
2007-01-01	77.7813370294144
2008-01-01	76.4129745562402
2009-01-01	71.9531566482364
2010-01-01	71.0522631455332
2011-01-01	71.3853748550082
2012-01-01	72.2573578142578
2013-01-01	72.5550961466472
2014-01-01	73.4757602584918
2015-01-01	74.1843713161981
2016-01-01	74.8343589567450
2017-01-01	75.4428426381162