Year	Percent
1991-01-01	54.5040016174316
1992-01-01	54.6860008239746
1993-01-01	54.8219985961914
1994-01-01	54.9049987792969
1995-01-01	54.9389991760254
1996-01-01	54.8800010681152
1997-01-01	54.7589988708496
1998-01-01	54.5789985656738
1999-01-01	54.3470001220703
2000-01-01	54.0670013427734
2001-01-01	53.8349990844727
2002-01-01	53.5499992370605
2003-01-01	53.2319984436035
2004-01-01	52.9059982299805
2005-01-01	52.6240005493164
2006-01-01	52.5960006713867
2007-01-01	52.6030006408691
2008-01-01	52.6769981384277
2009-01-01	52.8069992065430
2010-01-01	52.9239997863770
2011-01-01	53.0629997253418
2012-01-01	53.2270011901855
2013-01-01	53.4150009155273
2014-01-01	53.6049995422363
2015-01-01	53.7939987182617
2016-01-01	53.8909988403320
2017-01-01	54.1520004272461