Year	Percent
1991-01-01	24.3467774818607
1992-01-01	25.1444758244112
1993-01-01	26.5478038303501
1994-01-01	27.0618028340741
1995-01-01	24.6021135684141
1996-01-01	22.8811917044884
1997-01-01	19.8158860555040
1998-01-01	19.3875753931115
1999-01-01	23.7912367523123
2000-01-01	26.8451556986700
2001-01-01	28.7382261169636
2002-01-01	29.9535615892046
2003-01-01	29.0717046489423
2004-01-01	29.1393884696261
2005-01-01	27.1772492315425
2006-01-01	23.7635396817124
2007-01-01	18.6932209048907
2008-01-01	16.7032574786339
2009-01-01	21.5737006423145
2010-01-01	24.4541101655301
2011-01-01	25.5339531335213
2012-01-01	26.1921163488894
2013-01-01	26.5904127558654
2014-01-01	23.5603361980904
2015-01-01	20.6621622472565
2016-01-01	17.6492042263448
2017-01-01	15.0235457417677