Year	Percent
1991-01-01	61.9533867323131
1992-01-01	61.9761960460277
1993-01-01	61.7634059014543
1994-01-01	61.6694823064177
1995-01-01	61.4374859285119
1996-01-01	61.2866794481266
1997-01-01	61.1398182158060
1998-01-01	60.8846266883678
1999-01-01	60.8164935193967
2000-01-01	60.7847133983515
2001-01-01	60.6394177658073
2002-01-01	60.4676117500919
2003-01-01	60.3614316922570
2004-01-01	60.3803619475995
2005-01-01	60.4607258372347
2006-01-01	60.4277466707982
2007-01-01	60.3588567766681
2008-01-01	60.0169788717957
2009-01-01	59.4355317267422
2010-01-01	59.1656173865030
2011-01-01	59.0574448933923
2012-01-01	58.9147949871515
2013-01-01	58.8667724372287
2014-01-01	58.8346870454731
2015-01-01	58.7368470320061
2016-01-01	58.6695415692022
2017-01-01	58.5459460525260