Year	Percent
1991-01-01	61.1170005798340
1992-01-01	61.0200004577637
1993-01-01	59.3339996337891
1994-01-01	59.3269996643066
1995-01-01	60.7820014953613
1996-01-01	60.9259986877441
1997-01-01	62.2260017395020
1998-01-01	62.1640014648438
1999-01-01	62.7830009460449
2000-01-01	62.8230018615723
2001-01-01	62.6860008239746
2002-01-01	63.2750015258789
2003-01-01	61.9799995422363
2004-01-01	62.5800018310547
2005-01-01	62.6790008544922
2006-01-01	63.6720008850098
2007-01-01	63.3479995727539
2008-01-01	63.7859992980957
2009-01-01	61.3969993591309
2010-01-01	59.5649986267090
2011-01-01	59.1160011291504
2012-01-01	58.4179992675781
2013-01-01	57.9609985351563
2014-01-01	57.9949989318848
2015-01-01	58.1969985961914
2016-01-01	59.3940010070801
2017-01-01	59.5110015869141