Year	Percent
1991-01-01	11.7317515029348
1992-01-01	11.1808769149327
1993-01-01	11.2371470158352
1994-01-01	11.4657159877331
1995-01-01	12.0204213610459
1996-01-01	12.2110771534281
1997-01-01	12.7081556348868
1998-01-01	13.4358259133232
1999-01-01	13.6872749695524
2000-01-01	13.6947621812918
2001-01-01	13.6175703138230
2002-01-01	13.7187339610623
2003-01-01	13.5042155592498
2004-01-01	13.2185735363159
2005-01-01	13.1024508758735
2006-01-01	12.7192799092541
2007-01-01	12.2323703550294
2008-01-01	12.6789921033671
2009-01-01	13.0071241035639
2010-01-01	12.3685346253525
2011-01-01	12.3486790434709
2012-01-01	12.5818464935067
2013-01-01	12.5616604637890
2014-01-01	12.5144404826021
2015-01-01	13.0123555049234
2016-01-01	13.5255322707365
2017-01-01	13.7026938225576