Year	Percent
1968-01-01	96.7145876525896
1969-01-01	96.6313065254107
1970-01-01	96.6252025827204
1971-01-01	96.8163967678374
1972-01-01	96.6378647381926
1973-01-01	96.8844867062129
1974-01-01	96.7222466341610
1975-01-01	96.0270426590781
1976-01-01	95.8865065026583
1977-01-01	95.8494052656102
1978-01-01	95.6969678149790
1979-01-01	96.1044263506268
1980-01-01	96.0868205883491
1981-01-01	95.8665337121185
1982-01-01	95.9072101695568
1983-01-01	95.7712749946056
1984-01-01	95.8103508663644
1985-01-01	95.6340004751253
1986-01-01	95.5397613010033
1987-01-01	95.4947665181738
1988-01-01	95.9201092691958
1989-01-01	96.2113345489993
1990-01-01	96.3491254510272
1991-01-01	96.4828683577922
1992-01-01	96.5185795173045
1993-01-01	96.1839523519585
1994-01-01	95.5458347522725
1995-01-01	95.3225446769767
1996-01-01	95.3015527455165
1997-01-01	95.2321300162278
1998-01-01	94.3756696884299
1999-01-01	93.7776095374032
2000-01-01	93.5917876378994
2001-01-01	92.8920902188002
2002-01-01	92.1385105567636
2003-01-01	92.1627316546370
2004-01-01	92.2220777211015
2005-01-01	92.3164111560118
2006-01-01	92.5543338664960
2007-01-01	92.9354369036500
2008-01-01	92.6610402525726
2009-01-01	91.4283633572743
2010-01-01	91.5378552335121
2011-01-01	91.7168247737054
2012-01-01	91.5910346774825
2013-01-01	91.7500793903920
2014-01-01	92.2101090132613
2015-01-01	92.2402785848249
2016-01-01	92.5818064455153
2017-01-01	92.8176873729478