Year	Percent
1991-01-01	14.1355657802527
1992-01-01	14.9397841637474
1993-01-01	16.4765987080700
1994-01-01	16.8576294688067
1995-01-01	17.0852879451876
1996-01-01	17.0965532981058
1997-01-01	16.3795871548935
1998-01-01	15.8950434368279
1999-01-01	16.0869606444190
2000-01-01	15.3977815282338
2001-01-01	15.6854567699397
2002-01-01	16.6537370720709
2003-01-01	16.5342706360980
2004-01-01	16.0769112535034
2005-01-01	15.6463474352992
2006-01-01	14.6868515965352
2007-01-01	13.4769362135479
2008-01-01	14.0498536127147
2009-01-01	17.7824590663198
2010-01-01	18.3203780479038
2011-01-01	18.0532028528086
2012-01-01	18.3180545938942
2013-01-01	18.3808965309973
2014-01-01	17.2593437257021
2015-01-01	16.0018885773304
2016-01-01	15.0296277671364
2017-01-01	13.8451695320210