Year	Percent
1991-01-01	38.7729988098145
1992-01-01	38.9220008850098
1993-01-01	38.7089996337891
1994-01-01	38.6640014648438
1995-01-01	38.5880012512207
1996-01-01	38.6069984436035
1997-01-01	38.5460014343262
1998-01-01	38.6189994812012
1999-01-01	38.9300003051758
2000-01-01	38.9939994812012
2001-01-01	38.9420013427734
2002-01-01	39.0660018920898
2003-01-01	39.1230010986328
2004-01-01	39.2869987487793
2005-01-01	39.4949989318848
2006-01-01	39.4300003051758
2007-01-01	39.1209983825684
2008-01-01	39.2830009460449
2009-01-01	39.4220008850098
2010-01-01	39.1889991760254
2011-01-01	39.3989982604980
2012-01-01	39.7089996337891
2013-01-01	39.9949989318848
2014-01-01	40.3499984741211
2015-01-01	40.7070007324219
2016-01-01	41.0139999389648
2017-01-01	41.3219985961914