Year	Percent
1991-01-01	54.7809982299805
1992-01-01	54.3149986267090
1993-01-01	53.3989982604980
1994-01-01	53.2630004882813
1995-01-01	53.6510009765625
1996-01-01	53.6290016174316
1997-01-01	54.4550018310547
1998-01-01	54.9099998474121
1999-01-01	53.8419990539551
2000-01-01	53.4109992980957
2001-01-01	54.2589988708496
2002-01-01	54.5579986572266
2003-01-01	52.8079986572266
2004-01-01	55.4269981384277
2005-01-01	55.3540000915527
2006-01-01	55.7540016174316
2007-01-01	56.8810005187988
2008-01-01	56.8819999694824
2009-01-01	55.9440002441406
2010-01-01	54.9440002441406
2011-01-01	53.3160018920898
2012-01-01	52.6110000610352
2013-01-01	51.6319999694824
2014-01-01	52.1139984130859
2015-01-01	52.2270011901855
2016-01-01	52.1430015563965
2017-01-01	52.5660018920898