Year	Percent
1991-01-01	62.5940017700195
1992-01-01	62.8110008239746
1993-01-01	62.4230003356934
1994-01-01	61.9780006408691
1995-01-01	61.6160011291504
1996-01-01	61.5600013732910
1997-01-01	61.7169990539551
1998-01-01	60.9339981079102
1999-01-01	60.0909996032715
2000-01-01	59.6430015563965
2001-01-01	59.0999984741211
2002-01-01	58.2309989929199
2003-01-01	57.9630012512207
2004-01-01	57.8470001220703
2005-01-01	57.9360008239746
2006-01-01	58.0320014953613
2007-01-01	58.3650016784668
2008-01-01	58.1660003662109
2009-01-01	57.3059997558594
2010-01-01	57.0309982299805
2011-01-01	56.8180007934570
2012-01-01	56.7039985656738
2013-01-01	57.2179985046387
2014-01-01	57.6730003356934
2015-01-01	57.9920005798340
2016-01-01	58.5639991760254
2017-01-01	58.5089988708496