Year	Percent
1991-01-01	50.9910011291504
1992-01-01	52.5760002136230
1993-01-01	53.7159996032715
1994-01-01	52.8860015869141
1995-01-01	52.5610008239746
1996-01-01	51.5069999694824
1997-01-01	51.9199981689453
1998-01-01	52.1809997558594
1999-01-01	50.2750015258789
2000-01-01	49.4860000610352
2001-01-01	49.4830017089844
2002-01-01	49.2519989013672
2003-01-01	49.7379989624023
2004-01-01	50.9049987792969
2005-01-01	50.9029998779297
2006-01-01	51.7120018005371
2007-01-01	53.3979988098145
2008-01-01	53.8390007019043
2009-01-01	52.4169998168945
2010-01-01	55.6419982910156
2011-01-01	57.4199981689453
2012-01-01	57.7739982604980
2013-01-01	58.1399993896484
2014-01-01	58.0550003051758
2015-01-01	58.2120018005371
2016-01-01	57.9529991149902
2017-01-01	57.9679985046387