Year	Percent
1991-01-01	56.4599990844727
1992-01-01	55.2799987792969
1993-01-01	53.8510017395020
1994-01-01	53.4220008850098
1995-01-01	53.4449996948242
1996-01-01	52.8559989929199
1997-01-01	52.4210014343262
1998-01-01	52.4469985961914
1999-01-01	53.1629981994629
2000-01-01	53.4700012207031
2001-01-01	53.4640007019043
2002-01-01	52.9519996643066
2003-01-01	52.2459983825684
2004-01-01	51.4129981994629
2005-01-01	51.9300003051758
2006-01-01	52.8180007934570
2007-01-01	54.0670013427734
2008-01-01	54.7610015869141
2009-01-01	54.7639999389648
2010-01-01	55.2980003356934
2011-01-01	56.5299987792969
2012-01-01	56.7610015869141
2013-01-01	57.1660003662109
2014-01-01	57.3709983825684
2015-01-01	57.4949989318848
2016-01-01	58.0000000000000
2017-01-01	58.2109985351563