Year	Percent
1991-01-01	42.1349983215332
1992-01-01	42.2939987182617
1993-01-01	42.4150009155273
1994-01-01	42.4760017395020
1995-01-01	42.4589996337891
1996-01-01	42.2190017700195
1997-01-01	41.7070007324219
1998-01-01	41.5509986877441
1999-01-01	41.3819999694824
2000-01-01	41.2159996032715
2001-01-01	41.1170005798340
2002-01-01	41.0309982299805
2003-01-01	40.9599990844727
2004-01-01	40.9280014038086
2005-01-01	40.9399986267090
2006-01-01	40.8979988098145
2007-01-01	37.6090011596680
2008-01-01	37.6800003051758
2009-01-01	37.8120002746582
2010-01-01	37.9900016784668
2011-01-01	38.2700004577637
2012-01-01	38.5859985351563
2013-01-01	38.9220008850098
2014-01-01	39.2659988403320
2015-01-01	39.6030006408691
2016-01-01	39.7960014343262
2017-01-01	39.9589996337891