Year	Percent
1991-01-01	22.1560001373291
1992-01-01	23.0219993591309
1993-01-01	22.8269996643066
1994-01-01	27.2409992218018
1995-01-01	24.7150001525879
1996-01-01	21.0259990692139
1997-01-01	22.5440006256104
1998-01-01	23.0849990844727
1999-01-01	31.8929996490479
2000-01-01	36.7260017395020
2001-01-01	38.6570014953613
2002-01-01	37.6040000915527
2003-01-01	33.0089988708496
2004-01-01	32.8670005798340
2005-01-01	30.1280002593994
2006-01-01	26.7140007019043
2007-01-01	20.3889999389648
2008-01-01	19.0970001220703
2009-01-01	27.3840007781982
2010-01-01	33.6430015563965
2011-01-01	33.4650001525879
2012-01-01	34.0509986877441
2013-01-01	33.7000007629395
2014-01-01	29.7089996337891
2015-01-01	26.4950008392334
2016-01-01	22.2150001525879
2017-01-01	19.0170001983643