Year	Percent
1991-01-01	56.8849983215332
1992-01-01	57.4739990234375
1993-01-01	58.1129989624023
1994-01-01	57.3950004577637
1995-01-01	55.7029991149902
1996-01-01	56.7330017089844
1997-01-01	58.8110008239746
1998-01-01	58.9749984741211
1999-01-01	58.9309997558594
2000-01-01	58.7719993591309
2001-01-01	58.2050018310547
2002-01-01	58.1769981384277
2003-01-01	57.6180000305176
2004-01-01	58.4799995422363
2005-01-01	58.8740005493164
2006-01-01	59.5989990234375
2007-01-01	59.6640014648438
2008-01-01	59.2470016479492
2009-01-01	58.2509994506836
2010-01-01	58.0989990234375
2011-01-01	58.2169990539551
2012-01-01	59.0299987792969
2013-01-01	58.8100013732910
2014-01-01	58.2890014648438
2015-01-01	58.6899986267090
2016-01-01	58.9020004272461
2017-01-01	59.2140007019043