Year	Percent
1991-01-01	42.3429985046387
1992-01-01	41.7599983215332
1993-01-01	42.1720008850098
1994-01-01	41.5610008239746
1995-01-01	41.0530014038086
1996-01-01	40.3660011291504
1997-01-01	39.9059982299805
1998-01-01	39.1679992675781
1999-01-01	38.1759986877441
2000-01-01	37.7029991149902
2001-01-01	37.3400001525879
2002-01-01	36.6619987487793
2003-01-01	36.1910018920898
2004-01-01	35.6129989624023
2005-01-01	34.9630012512207
2006-01-01	35.0519981384277
2007-01-01	35.5929985046387
2008-01-01	35.4599990844727
2009-01-01	35.4020004272461
2010-01-01	35.9599990844727
2011-01-01	36.0229988098145
2012-01-01	35.9480018615723
2013-01-01	36.0000000000000
2014-01-01	35.9710006713867
2015-01-01	35.9780006408691
2016-01-01	35.8709983825684
2017-01-01	35.8919982910156