Year	Percent
1991-01-01	38.6650009155273
1992-01-01	39.1440010070801
1993-01-01	39.1380004882813
1994-01-01	35.8730010986328
1995-01-01	36.5649986267090
1996-01-01	35.0559997558594
1997-01-01	36.7260017395020
1998-01-01	36.3499984741211
1999-01-01	37.0750007629395
2000-01-01	34.9529991149902
2001-01-01	36.0559997558594
2002-01-01	35.8160018920898
2003-01-01	35.6310005187988
2004-01-01	35.3330001831055
2005-01-01	35.2900009155273
2006-01-01	37.9179992675781
2007-01-01	40.5029983520508
2008-01-01	41.4539985656738
2009-01-01	40.2569999694824
2010-01-01	39.7010002136230
2011-01-01	39.3950004577637
2012-01-01	39.6710014343262
2013-01-01	39.6660003662109
2014-01-01	40.2449989318848
2015-01-01	40.3170013427734
2016-01-01	40.0620002746582
2017-01-01	40.6520004272461