Year	Percent
1991-01-01	55.3139991760254
1992-01-01	56.9199981689453
1993-01-01	57.7000007629395
1994-01-01	57.9440002441406
1995-01-01	58.3170013427734
1996-01-01	56.3320007324219
1997-01-01	55.9099998474121
1998-01-01	55.8230018615723
1999-01-01	55.4700012207031
2000-01-01	55.8419990539551
2001-01-01	56.4210014343262
2002-01-01	56.9889984130859
2003-01-01	57.4650001525879
2004-01-01	58.2879981994629
2005-01-01	58.8129997253418
2006-01-01	59.3540000915527
2007-01-01	59.5740013122559
2008-01-01	59.9850006103516
2009-01-01	60.2750015258789
2010-01-01	60.4049987792969
2011-01-01	60.4869995117188
2012-01-01	60.9379997253418
2013-01-01	61.3390007019043
2014-01-01	61.8580017089844
2015-01-01	62.2649993896484
2016-01-01	62.9350013732910
2017-01-01	62.7799987792969