Year	Percent
1991-01-01	62.5449981689453
1992-01-01	61.4980010986328
1993-01-01	60.9189987182617
1994-01-01	60.7029991149902
1995-01-01	59.9389991760254
1996-01-01	59.8320007324219
1997-01-01	59.9480018615723
1998-01-01	58.4700012207031
1999-01-01	57.4160003662109
2000-01-01	58.2249984741211
2001-01-01	58.0960006713867
2002-01-01	57.0810012817383
2003-01-01	56.3989982604980
2004-01-01	57.0149993896484
2005-01-01	57.4939994812012
2006-01-01	57.8989982604980
2007-01-01	58.3979988098145
2008-01-01	58.2089996337891
2009-01-01	57.0639991760254
2010-01-01	56.5660018920898
2011-01-01	57.5449981689453
2012-01-01	58.2159996032715
2013-01-01	58.7700004577637
2014-01-01	58.7459983825684
2015-01-01	58.8209991455078
2016-01-01	58.5960006713867
2017-01-01	58.5099983215332