Year	Percent
1991-01-01	52.7259050662334
1992-01-01	53.3502345824448
1993-01-01	53.5148960859084
1994-01-01	54.4118974440947
1995-01-01	54.6025336650501
1996-01-01	54.7860809942141
1997-01-01	54.6377754690838
1998-01-01	54.6658897274101
1999-01-01	54.7585301570240
2000-01-01	54.9316596906829
2001-01-01	55.4109809255819
2002-01-01	55.3665516240596
2003-01-01	56.1518603434590
2004-01-01	56.9682715686625
2005-01-01	57.4559052371408
2006-01-01	58.4876775558213
2007-01-01	58.8407055826674
2008-01-01	58.6550230907924
2009-01-01	57.7877860272633
2010-01-01	57.4393899922780
2011-01-01	57.5887259333721
2012-01-01	57.1849283903078
2013-01-01	57.0124212696029
2014-01-01	57.4002447785555
2015-01-01	57.4670482623722
2016-01-01	57.5537295723917
2017-01-01	57.6973942410399