Year	Percent
1960-01-01	84.9930321993537
1961-01-01	84.9821583073208
1962-01-01	84.3215953893498
1963-01-01	83.1433372487026
1964-01-01	82.1786682801621
1965-01-01	81.7387400541432
1966-01-01	81.7254475744380
1967-01-01	81.7002675402844
1968-01-01	82.2153081467706
1969-01-01	81.9858265451853
1970-01-01	81.9100491858130
1971-01-01	82.3188027338614
1972-01-01	82.2410486058696
1973-01-01	82.2939602200928
1974-01-01	82.0246188422811
1975-01-01	81.5727042953131
1976-01-01	81.3467807643714
1977-01-01	80.7795939563425
1978-01-01	80.6069056766324
1979-01-01	80.4307204888121
1980-01-01	80.1396929083349
1981-01-01	80.1257890752382
1982-01-01	79.8410719356492
1983-01-01	79.8220898691884
1984-01-01	79.2550220825578
1985-01-01	78.6118711495307
1986-01-01	78.2581412785673
1987-01-01	77.8012623712884
1988-01-01	77.5172213840105
1989-01-01	77.4057675108966
1990-01-01	77.5865330042163
1991-01-01	77.9745736734121
1992-01-01	78.1566204409336
1993-01-01	78.1365518090484
1994-01-01	77.8789182158542
1995-01-01	77.6907538840613
1996-01-01	77.7937368698026
1997-01-01	77.8387106192738
1998-01-01	77.3738530098286
1999-01-01	77.0399734426297
2000-01-01	76.5064536401120
2001-01-01	75.7624444886022
2002-01-01	74.7901015449773
2003-01-01	74.1900540761766
2004-01-01	73.5265830945336
2005-01-01	73.3662760572932
2006-01-01	73.2565390553042
2007-01-01	73.2227547254921
2008-01-01	72.8638598951742
2009-01-01	72.1371280650031
2010-01-01	71.7890817486566
2011-01-01	71.3136715286567
2012-01-01	70.7977241662680
2013-01-01	70.5890350531647
2014-01-01	70.4658907396656
2015-01-01	70.3744070578346
2016-01-01	70.5064081244384
2017-01-01	70.5626797943244