Year	Percent
1991-01-01	55.2971598635060
1992-01-01	54.8880036295262
1993-01-01	53.9921746950468
1994-01-01	53.2297144352675
1995-01-01	53.1356755322977
1996-01-01	52.8049293550238
1997-01-01	52.8799256684647
1998-01-01	52.6029485289292
1999-01-01	51.4703584945378
2000-01-01	50.2051208989506
2001-01-01	49.6393651867719
2002-01-01	47.9414197894228
2003-01-01	47.9380714425762
2004-01-01	47.7659902968202
2005-01-01	48.1276351706245
2006-01-01	49.2297981668700
2007-01-01	50.4754828263360
2008-01-01	51.3657959241808
2009-01-01	50.4412195280794
2010-01-01	50.0125955914790
2011-01-01	49.9106382870694
2012-01-01	50.1625585250147
2013-01-01	50.2508842171266
2014-01-01	51.2841737441517
2015-01-01	51.9893847683448
2016-01-01	52.7641524515892
2017-01-01	53.2095658443366