Year	Percent
1991-01-01	14.4898644244917
1992-01-01	14.4196556117574
1993-01-01	14.6083235434693
1994-01-01	14.6510726751313
1995-01-01	14.4167176647920
1996-01-01	15.1321333305330
1997-01-01	15.5533917890283
1998-01-01	15.9331271105920
1999-01-01	16.1357788630069
2000-01-01	15.5881806647490
2001-01-01	15.7870367390832
2002-01-01	15.7075952850471
2003-01-01	15.7003785500730
2004-01-01	15.3079124756651
2005-01-01	14.7967829413432
2006-01-01	14.4617123271337
2007-01-01	14.3168731001453
2008-01-01	14.0258104460267
2009-01-01	14.1567965563351
2010-01-01	14.1591684878533
2011-01-01	13.7286075631976
2012-01-01	13.4306534042538
2013-01-01	13.1895836120709
2014-01-01	12.8037414222815
2015-01-01	12.7649414716994
2016-01-01	13.8020011822669
2017-01-01	13.8613287498653