Year	Percent
1991-01-01	56.8843333418050
1992-01-01	57.1190438229560
1993-01-01	57.7121672823516
1994-01-01	57.8389248192717
1995-01-01	57.7430469828308
1996-01-01	57.6789082284932
1997-01-01	58.3423724334258
1998-01-01	58.1575342454857
1999-01-01	57.7354370780548
2000-01-01	57.8630480987110
2001-01-01	58.4930081899108
2002-01-01	58.7833653785185
2003-01-01	58.7907091256154
2004-01-01	59.7934843960777
2005-01-01	60.3210574303569
2006-01-01	61.1749740715441
2007-01-01	61.4001078852114
2008-01-01	61.5376557529379
2009-01-01	61.1157257982087
2010-01-01	61.0088233815423
2011-01-01	60.8546713065272
2012-01-01	61.0211042204996
2013-01-01	60.8639520227543
2014-01-01	60.8260290546705
2015-01-01	60.5288144642484
2016-01-01	59.6569985187211
2017-01-01	59.2661373927372