Year	Percent
1968-01-01	76.3019991753116
1969-01-01	75.9819865990771
1970-01-01	75.7948060976629
1971-01-01	75.2539167206981
1972-01-01	75.2070620579475
1973-01-01	75.7710404570861
1974-01-01	75.1445246382934
1975-01-01	74.7982828261064
1976-01-01	75.1570522551887
1977-01-01	75.8424532813438
1978-01-01	76.4954189156720
1979-01-01	76.9876716562553
1980-01-01	77.1897924439083
1981-01-01	77.4278138077602
1982-01-01	77.9662110085285
1983-01-01	78.7549233256792
1984-01-01	79.0051195498514
1985-01-01	79.1006269561258
1986-01-01	79.3223940563087
1987-01-01	79.6245325704383
1988-01-01	80.1037872061850
1989-01-01	80.7026727261269
1990-01-01	81.1772377744416
1991-01-01	81.6525231386136
1992-01-01	81.8166907126061
1993-01-01	81.6290832196248
1994-01-01	81.5045518106519
1995-01-01	81.4888371767274
1996-01-01	81.8498733417986
1997-01-01	82.3285353332266
1998-01-01	82.1510776938885
1999-01-01	82.0482663078359
2000-01-01	82.0438295466051
2001-01-01	82.2494388135186
2002-01-01	82.1217254668172
2003-01-01	82.2881012824888
2004-01-01	82.3632002215563
2005-01-01	82.6083399587286
2006-01-01	82.9543229252689
2007-01-01	83.3837886653067
2008-01-01	83.5224175993465
2009-01-01	83.8815074396727
2010-01-01	84.1443309337084
2011-01-01	84.3113070377834
2012-01-01	84.0803427094492
2013-01-01	84.8589751939666
2014-01-01	85.2682809109482
2015-01-01	85.5753803264814
2016-01-01	86.1340091213863
2017-01-01	86.6583378439034