Year	Percent
1991-01-01	25.8667481519726
1992-01-01	25.4574248653606
1993-01-01	26.8783558162513
1994-01-01	27.8292013315061
1995-01-01	28.9291863845930
1996-01-01	25.6399883212592
1997-01-01	24.8118253047104
1998-01-01	25.8675963362276
1999-01-01	24.7164027275968
2000-01-01	26.8970671422839
2001-01-01	28.0116613119788
2002-01-01	27.6734043078213
2003-01-01	26.9537916914844
2004-01-01	24.5465824519596
2005-01-01	25.6650917832416
2006-01-01	24.5534813503258
2007-01-01	23.5506634651861
2008-01-01	24.0992091029141
2009-01-01	23.6073355770953
2010-01-01	25.9136435398496
2011-01-01	26.9981972825546
2012-01-01	28.7005959866359
2013-01-01	27.4785513306485
2014-01-01	27.3537131927457
2015-01-01	28.2803336729820
2016-01-01	28.1603505267015
2017-01-01	28.4477755513006