Year	Percent
1968-01-01	97.6517627853065
1969-01-01	97.5087380910824
1970-01-01	97.5211698123011
1971-01-01	97.6918057564329
1972-01-01	97.6766615350260
1973-01-01	97.8333203879882
1974-01-01	97.7437291022794
1975-01-01	97.5230342283518
1976-01-01	97.5660045433445
1977-01-01	97.4105923169472
1978-01-01	97.4958635919159
1979-01-01	97.6607153951768
1980-01-01	97.5600861470981
1981-01-01	97.5155850119807
1982-01-01	97.6268893204575
1983-01-01	97.7285948142894
1984-01-01	97.6861608870354
1985-01-01	97.4648039323103
1986-01-01	97.4299793293036
1987-01-01	97.4755474878222
1988-01-01	97.5991801780788
1989-01-01	97.6849604989874
1990-01-01	97.7023581206217
1991-01-01	97.8160786801358
1992-01-01	97.9276887000786
1993-01-01	97.8612272679970
1994-01-01	97.5358641166606
1995-01-01	97.5437617197380
1996-01-01	97.7131936637663
1997-01-01	97.7062352435370
1998-01-01	97.4169318677918
1999-01-01	97.3637453853089
2000-01-01	97.3246054445567
2001-01-01	97.0010983352285
2002-01-01	96.6456463180591
2003-01-01	96.5712047541166
2004-01-01	96.3638953086313
2005-01-01	96.1836774679987
2006-01-01	96.2754883814430
2007-01-01	96.3765636083099
2008-01-01	96.2553253431660
2009-01-01	96.1288860969789
2010-01-01	96.2526220600438
2011-01-01	96.0530992183500
2012-01-01	95.6662337010478
2013-01-01	95.7151574892943
2014-01-01	95.6145387933204
2015-01-01	95.5533484119853
2016-01-01	95.6464609160772
2017-01-01	95.5904929896409