Year	Percent
1991-01-01	19.7569999694824
1992-01-01	19.7399997711182
1993-01-01	19.7530002593994
1994-01-01	19.8029994964600
1995-01-01	19.8500003814697
1996-01-01	19.8540000915527
1997-01-01	19.7830009460449
1998-01-01	19.8369998931885
1999-01-01	19.8250007629395
2000-01-01	20.1580009460449
2001-01-01	20.5860004425049
2002-01-01	20.8530006408691
2003-01-01	21.2269992828369
2004-01-01	21.5739994049072
2005-01-01	21.8889999389648
2006-01-01	22.3390007019043
2007-01-01	22.8090000152588
2008-01-01	23.0949993133545
2009-01-01	25.9260005950928
2010-01-01	26.0580005645752
2011-01-01	26.0419998168945
2012-01-01	26.0410003662109
2013-01-01	26.1170005798340
2014-01-01	26.1490001678467
2015-01-01	26.2010002136230
2016-01-01	26.2509994506836
2017-01-01	26.2049999237061