Year	Percent
1986-01-01	24.6561112598629
1987-01-01	24.8189675686121
1988-01-01	26.2633354116631
1989-01-01	27.4965623114255
1990-01-01	27.0207650901887
1991-01-01	26.8941695520178
1992-01-01	27.2160557886980
1993-01-01	27.1606286884401
1994-01-01	26.2715481564127
1995-01-01	25.4798237728371
1996-01-01	24.5812052363099
1997-01-01	24.6575947391223
1998-01-01	25.0703194207569
1999-01-01	25.1095744980088
2000-01-01	25.0019630870059
2001-01-01	24.4409415379710
2002-01-01	23.8143668713650
2003-01-01	24.1792877037202
2004-01-01	23.7152801300775
2005-01-01	22.7897236732083
2006-01-01	22.1873185572912
2007-01-01	21.9966616194523
2008-01-01	22.2019992245900
2009-01-01	22.5624823787283
2010-01-01	22.9030565432970
2011-01-01	22.7061910951553
2012-01-01	22.8911793138650
2013-01-01	22.5111770270160
2014-01-01	21.3617786771000
2015-01-01	21.3150198108955
2016-01-01	20.1551415107520
2017-01-01	19.1315578953731