Year	Percent
1991-01-01	50.5699996948242
1992-01-01	50.4589996337891
1993-01-01	50.3330001831055
1994-01-01	50.1839981079102
1995-01-01	49.9469985961914
1996-01-01	49.8019981384277
1997-01-01	49.5950012207031
1998-01-01	49.3339996337891
1999-01-01	49.0719985961914
2000-01-01	48.8569984436035
2001-01-01	48.7229995727539
2002-01-01	48.6399993896484
2003-01-01	47.9519996643066
2004-01-01	47.2910003662109
2005-01-01	46.6489982604980
2006-01-01	46.1049995422363
2007-01-01	46.9889984130859
2008-01-01	47.8979988098145
2009-01-01	48.8240013122559
2010-01-01	49.7529983520508
2011-01-01	50.6699981689453
2012-01-01	51.5320014953613
2013-01-01	52.4010009765625
2014-01-01	53.2519989013672
2015-01-01	54.1730003356934
2016-01-01	54.2309989929199
2017-01-01	54.4319992065430