Year	Percent
1991-01-01	12.0107983849488
1992-01-01	11.6864360204645
1993-01-01	11.9747805400576
1994-01-01	12.1961224840490
1995-01-01	12.6464851202362
1996-01-01	12.8147094781783
1997-01-01	13.1029819923816
1998-01-01	13.5927342429125
1999-01-01	13.8195590875442
2000-01-01	13.7358313704701
2001-01-01	13.7329673989122
2002-01-01	13.9198425081896
2003-01-01	13.7044277006204
2004-01-01	13.4315940219138
2005-01-01	13.2533014728955
2006-01-01	12.8357138691540
2007-01-01	12.2948370054766
2008-01-01	12.7250670172415
2009-01-01	13.3941083069660
2010-01-01	13.0160817563275
2011-01-01	13.0017394678958
2012-01-01	13.1676877794520
2013-01-01	13.1285227755546
2014-01-01	12.9113421483020
2015-01-01	13.1473392875608
2016-01-01	13.3986752353184
2017-01-01	13.3698702771604