Year	Percent
1991-01-01	71.1819992065430
1992-01-01	71.3779983520508
1993-01-01	71.1090011596680
1994-01-01	71.3310012817383
1995-01-01	71.1110000610352
1996-01-01	71.1589965820313
1997-01-01	71.2659988403320
1998-01-01	71.4059982299805
1999-01-01	71.4029998779297
2000-01-01	71.4499969482422
2001-01-01	71.4459991455078
2002-01-01	71.3059997558594
2003-01-01	71.1500015258789
2004-01-01	71.0869979858398
2005-01-01	71.0859985351563
2006-01-01	71.2710037231445
2007-01-01	71.4110031127930
2008-01-01	71.6770019531250
2009-01-01	71.8980026245117
2010-01-01	72.1470031738281
2011-01-01	72.4260025024414
2012-01-01	72.7020034790039
2013-01-01	72.8789978027344
2014-01-01	72.6529998779297
2015-01-01	72.5199966430664
2016-01-01	72.3280029296875
2017-01-01	72.4430007934570