Year	Percent
1991-01-01	62.1100006103516
1992-01-01	60.3849983215332
1993-01-01	58.2869987487793
1994-01-01	57.3660011291504
1995-01-01	55.7939987182617
1996-01-01	55.1300010681152
1997-01-01	55.1790008544922
1998-01-01	54.6829986572266
1999-01-01	52.3740005493164
2000-01-01	51.1170005798340
2001-01-01	50.4690017700195
2002-01-01	51.1360015869141
2003-01-01	52.1980018615723
2004-01-01	52.8730010986328
2005-01-01	53.9150009155273
2006-01-01	56.9970016479492
2007-01-01	57.8880004882813
2008-01-01	58.0050010681152
2009-01-01	52.6279983520508
2010-01-01	50.4150009155273
2011-01-01	53.6549987792969
2012-01-01	55.1370010375977
2013-01-01	55.9959983825684
2014-01-01	56.6580009460449
2015-01-01	58.3470001220703
2016-01-01	58.6920013427734
2017-01-01	59.1349983215332