Year	Percent
1991-01-01	14.1319999694824
1992-01-01	14.6160001754761
1993-01-01	14.7519998550415
1994-01-01	15.2749996185303
1995-01-01	15.7180004119873
1996-01-01	16.0310001373291
1997-01-01	16.1730003356934
1998-01-01	16.6490001678467
1999-01-01	17.2700004577637
2000-01-01	17.6359996795654
2001-01-01	17.9969997406006
2002-01-01	18.3969993591309
2003-01-01	18.6669998168945
2004-01-01	18.8479995727539
2005-01-01	19.1809997558594
2006-01-01	19.7880001068115
2007-01-01	19.8099994659424
2008-01-01	19.9880008697510
2009-01-01	20.3320007324219
2010-01-01	21.0130004882813
2011-01-01	21.3990001678467
2012-01-01	21.4829998016357
2013-01-01	21.5510005950928
2014-01-01	26.1350002288818
2015-01-01	26.2679996490479
2016-01-01	27.2999992370605
2017-01-01	28.1490001678467