Year	Percent
1991-01-01	58.1673676160561
1992-01-01	58.2926208207603
1993-01-01	58.2800680715281
1994-01-01	58.3582739368441
1995-01-01	58.0384234068266
1996-01-01	57.8376451922051
1997-01-01	57.5463994892862
1998-01-01	57.3960177612103
1999-01-01	57.3133689803406
2000-01-01	57.0791161634365
2001-01-01	57.1637933082086
2002-01-01	57.1881510327351
2003-01-01	57.3510159402130
2004-01-01	57.4617371858862
2005-01-01	57.5924998768025
2006-01-01	57.3237906253593
2007-01-01	56.9232650779677
2008-01-01	56.4863600064173
2009-01-01	56.1450928333367
2010-01-01	55.8659819621355
2011-01-01	55.6298594435467
2012-01-01	55.2924882971977
2013-01-01	55.3259634741857
2014-01-01	55.2991775503292
2015-01-01	55.0863046828086
2016-01-01	55.1097317753385
2017-01-01	55.0416991652639