Year	Percent
1991-01-01	69.2450027465820
1992-01-01	69.3789978027344
1993-01-01	69.5120010375977
1994-01-01	69.5500030517578
1995-01-01	69.5029983520508
1996-01-01	69.5759963989258
1997-01-01	69.6259994506836
1998-01-01	69.6090011596680
1999-01-01	69.5930023193359
2000-01-01	69.5979995727539
2001-01-01	69.6449966430664
2002-01-01	69.6539993286133
2003-01-01	69.6490020751953
2004-01-01	69.6330032348633
2005-01-01	69.6159973144531
2006-01-01	69.6729965209961
2007-01-01	69.6969985961914
2008-01-01	69.7060012817383
2009-01-01	69.7259979248047
2010-01-01	69.7259979248047
2011-01-01	69.7839965820313
2012-01-01	69.8190002441406
2013-01-01	69.8259963989258
2014-01-01	69.8000030517578
2015-01-01	69.7480010986328
2016-01-01	69.7480010986328
2017-01-01	69.7460021972656