Year	Percent
1991-01-01	58.5620002746582
1992-01-01	58.8530006408691
1993-01-01	58.1609992980957
1994-01-01	58.6599998474121
1995-01-01	58.0400009155273
1996-01-01	57.4630012512207
1997-01-01	57.7070007324219
1998-01-01	57.4269981384277
1999-01-01	57.0810012817383
2000-01-01	57.7750015258789
2001-01-01	59.6150016784668
2002-01-01	59.9690017700195
2003-01-01	60.4500007629395
2004-01-01	60.6940002441406
2005-01-01	59.6720008850098
2006-01-01	60.3689994812012
2007-01-01	61.0690002441406
2008-01-01	61.0970001220703
2009-01-01	60.1790008544922
2010-01-01	60.0359992980957
2011-01-01	58.2220001220703
2012-01-01	55.4309997558594
2013-01-01	52.7410011291504
2014-01-01	53.0760002136230
2015-01-01	53.2929992675781
2016-01-01	54.7260017395020
2017-01-01	55.8540000915527