Year	Percent
1991-01-01	35.5509986877441
1992-01-01	35.5499992370605
1993-01-01	35.4360008239746
1994-01-01	35.1829986572266
1995-01-01	35.1360015869141
1996-01-01	34.8199996948242
1997-01-01	34.5970001220703
1998-01-01	35.0750007629395
1999-01-01	35.8740005493164
2000-01-01	36.0180015563965
2001-01-01	36.9539985656738
2002-01-01	36.2560005187988
2003-01-01	33.9020004272461
2004-01-01	32.1790008544922
2005-01-01	33.1559982299805
2006-01-01	34.5289993286133
2007-01-01	35.4300003051758
2008-01-01	36.4580001831055
2009-01-01	37.5699996948242
2010-01-01	37.8160018920898
2011-01-01	38.0589981079102
2012-01-01	38.0250015258789
2013-01-01	39.5839996337891
2014-01-01	40.2190017700195
2015-01-01	41.0429992675781
2016-01-01	41.9309997558594
2017-01-01	42.6599998474121