Year	Percent
1991-01-01	58.5880012512207
1992-01-01	58.1899986267090
1993-01-01	57.9539985656738
1994-01-01	58.7809982299805
1995-01-01	59.1829986572266
1996-01-01	61.1930007934570
1997-01-01	62.8269996643066
1998-01-01	64.4169998168945
1999-01-01	64.5100021362305
2000-01-01	64.6370010375977
2001-01-01	64.4110031127930
2002-01-01	64.4189987182617
2003-01-01	63.0579986572266
2004-01-01	62.9290008544922
2005-01-01	62.5639991760254
2006-01-01	63.4480018615723
2007-01-01	64.7320022583008
2008-01-01	65.6959991455078
2009-01-01	64.3899993896484
2010-01-01	63.3870010375977
2011-01-01	63.1199989318848
2012-01-01	63.2579994201660
2013-01-01	62.7770004272461
2014-01-01	62.4659996032715
2015-01-01	62.0999984741211
2016-01-01	61.3590011596680
2017-01-01	61.5620002746582