Year	Percent
1986-01-01	95.8160248132162
1987-01-01	95.4850277653126
1988-01-01	94.4437888117250
1989-01-01	93.6666146977759
1990-01-01	93.2801961019494
1991-01-01	93.1396846810364
1992-01-01	92.8143999523007
1993-01-01	92.4756145084763
1994-01-01	91.9974538943500
1995-01-01	91.7637497450409
1996-01-01	91.6083949805352
1997-01-01	91.7629640235334
1998-01-01	91.1041606894519
1999-01-01	90.7307238094620
2000-01-01	91.1149555459588
2001-01-01	90.9797654347794
2002-01-01	91.2348549498346
2003-01-01	90.7558291201448
2004-01-01	91.3860320215945
2005-01-01	92.2673499908312
2006-01-01	92.2915751830601
2007-01-01	92.0834385123134
2008-01-01	91.7430003698625
2009-01-01	91.2783283705156
2010-01-01	91.6481838969705
2011-01-01	91.6901321126029
2012-01-01	91.0003562234630
2013-01-01	91.5608859998053
2014-01-01	92.2253154566440
2015-01-01	91.9736988386083
2016-01-01	92.8731739187236
2017-01-01	93.1037333559593