Year	Percent
1991-01-01	56.3219985961914
1992-01-01	56.3089981079102
1993-01-01	55.8559989929199
1994-01-01	57.9970016479492
1995-01-01	57.3349990844727
1996-01-01	56.0060005187988
1997-01-01	55.6220016479492
1998-01-01	57.8549995422363
1999-01-01	57.8720016479492
2000-01-01	57.2010002136230
2001-01-01	56.7000007629395
2002-01-01	56.9259986877441
2003-01-01	57.9630012512207
2004-01-01	56.8429985046387
2005-01-01	56.5390014648438
2006-01-01	57.3429985046387
2007-01-01	57.8919982910156
2008-01-01	58.0919990539551
2009-01-01	57.0589981079102
2010-01-01	58.3079986572266
2011-01-01	58.9160003662109
2012-01-01	59.4490013122559
2013-01-01	59.9039993286133
2014-01-01	59.2270011901855
2015-01-01	58.9620018005371
2016-01-01	58.4059982299805
2017-01-01	58.6450004577637