Year	Percent
1991-01-01	67.2822141978946
1992-01-01	67.4810930494171
1993-01-01	67.2584204895503
1994-01-01	66.9334626782170
1995-01-01	66.5835811919209
1996-01-01	66.3048010882215
1997-01-01	66.0189635555208
1998-01-01	65.4777124179855
1999-01-01	65.3108971983740
2000-01-01	65.2683174280161
2001-01-01	64.9143664212518
2002-01-01	64.5895680610176
2003-01-01	64.1360538388895
2004-01-01	63.9906895007581
2005-01-01	63.8474030734409
2006-01-01	63.7751987010386
2007-01-01	63.7568963903545
2008-01-01	63.3095669725230
2009-01-01	62.8397706886945
2010-01-01	62.5885582244084
2011-01-01	62.4846402506180
2012-01-01	62.3779646740472
2013-01-01	62.1864685408680
2014-01-01	61.9473305883475
2015-01-01	61.7076324614995
2016-01-01	61.3129976622872
2017-01-01	60.9360697756134