Year	Percent
1991-01-01	18.3500003814697
1992-01-01	15.3809995651245
1993-01-01	13.9890003204346
1994-01-01	15.9930000305176
1995-01-01	20.1970005035400
1996-01-01	20.0860004425049
1997-01-01	23.6000003814697
1998-01-01	26.8069992065430
1999-01-01	26.6919994354248
2000-01-01	20.7479991912842
2001-01-01	18.0240001678467
2002-01-01	17.4920005798340
2003-01-01	18.2269992828369
2004-01-01	17.2350006103516
2005-01-01	15.9149999618530
2006-01-01	15.7010002136230
2007-01-01	14.3179998397827
2008-01-01	14.0729999542236
2009-01-01	18.7040004730225
2010-01-01	17.1149997711182
2011-01-01	15.5220003128052
2012-01-01	14.9759998321533
2013-01-01	14.1999998092651
2014-01-01	14.0629997253418
2015-01-01	16.4160003662109
2016-01-01	16.6159992218018
2017-01-01	16.2520008087158