Year	Percent
1991-01-01	63.5673703343253
1992-01-01	63.7084586875212
1993-01-01	63.5711452751363
1994-01-01	63.4255477421964
1995-01-01	63.0934052697118
1996-01-01	62.8539202530306
1997-01-01	62.5647205896845
1998-01-01	62.2102718082077
1999-01-01	62.0744977949356
2000-01-01	61.9459998333950
2001-01-01	61.8059296079163
2002-01-01	61.6714223193136
2003-01-01	61.5261277579294
2004-01-01	61.5027241869075
2005-01-01	61.4935264692686
2006-01-01	61.3262972926405
2007-01-01	61.1294598067109
2008-01-01	60.7108179801962
2009-01-01	60.3356893718146
2010-01-01	60.0772292024530
2011-01-01	59.9135052548059
2012-01-01	59.7171738668222
2013-01-01	59.6455470600588
2014-01-01	59.5196066512702
2015-01-01	59.3063275102018
2016-01-01	59.1338830700081
2017-01-01	58.9375699006944