Year	Percent
1991-01-01	25.5639991760254
1992-01-01	27.2970008850098
1993-01-01	29.5130004882813
1994-01-01	31.9109992980957
1995-01-01	30.6149997711182
1996-01-01	28.0310001373291
1997-01-01	22.5060005187988
1998-01-01	21.0610008239746
1999-01-01	29.1329994201660
2000-01-01	35.1769981384277
2001-01-01	38.6809997558594
2002-01-01	41.0130004882813
2003-01-01	40.9959983825684
2004-01-01	39.7960014343262
2005-01-01	36.6419982910156
2006-01-01	29.6310005187988
2007-01-01	21.5429992675781
2008-01-01	17.1809997558594
2009-01-01	20.4950008392334
2010-01-01	23.6459999084473
2011-01-01	25.6770000457764
2012-01-01	26.4249992370605
2013-01-01	27.2049999237061
2014-01-01	23.7619991302490
2015-01-01	20.6900005340576
2016-01-01	17.5919990539551
2017-01-01	14.7790002822876