Year	Percent
1991-01-01	50.3940010070801
1992-01-01	50.4620018005371
1993-01-01	50.2500000000000
1994-01-01	49.4990005493164
1995-01-01	49.3639984130859
1996-01-01	49.3240013122559
1997-01-01	48.7169990539551
1998-01-01	48.6370010375977
1999-01-01	48.8940010070801
2000-01-01	49.1899986267090
2001-01-01	48.8050003051758
2002-01-01	47.9290008544922
2003-01-01	46.8959999084473
2004-01-01	44.7589988708496
2005-01-01	43.2439994812012
2006-01-01	43.0750007629395
2007-01-01	44.5699996948242
2008-01-01	46.2610015869141
2009-01-01	43.6899986267090
2010-01-01	41.0970001220703
2011-01-01	39.1769981384277
2012-01-01	38.9809989929199
2013-01-01	40.5890007019043
2014-01-01	42.3619995117188
2015-01-01	42.6889991760254
2016-01-01	45.6510009765625
2017-01-01	45.9570007324219