Year	Percent
1968-01-01	75.5474705376060
1969-01-01	75.3023869130209
1970-01-01	75.1072858523709
1971-01-01	74.5698763960258
1972-01-01	74.4044827996129
1973-01-01	75.0221758094473
1974-01-01	74.3046308919156
1975-01-01	73.6229127207165
1976-01-01	73.8953415606882
1977-01-01	74.5936487009694
1978-01-01	75.0721323592786
1979-01-01	75.6784596868544
1980-01-01	75.9125308662894
1981-01-01	76.0404299657414
1982-01-01	76.4851340285651
1983-01-01	77.0171511817554
1984-01-01	77.2756265464442
1985-01-01	77.4362395253082
1986-01-01	77.5781878724178
1987-01-01	77.8268796768562
1988-01-01	78.5209878776446
1989-01-01	79.2842879360234
1990-01-01	79.8439831003382
1991-01-01	80.3046977599270
1992-01-01	80.4092151045592
1993-01-01	79.9910895149906
1994-01-01	79.5910228754246
1995-01-01	79.3816733375304
1996-01-01	79.6268844931160
1997-01-01	80.0090127260741
1998-01-01	79.3326259014332
1999-01-01	78.7886813135802
2000-01-01	78.7135072242118
2001-01-01	78.6326945249361
2002-01-01	78.1202536231619
2003-01-01	78.4110408492427
2004-01-01	78.7685048153618
2005-01-01	79.1469952435812
2006-01-01	79.7269303911519
2007-01-01	80.3226504710793
2008-01-01	80.2912023118512
2009-01-01	79.7229804867354
2010-01-01	80.0559815424537
2011-01-01	80.5547013747166
2012-01-01	80.5152974766225
2013-01-01	81.4150551543904
2014-01-01	82.2034239840846
2015-01-01	82.6499336842224
2016-01-01	83.4266234547207
2017-01-01	84.1868464018974