Year	Percent
1991-01-01	22.1480007171631
1992-01-01	24.0139999389648
1993-01-01	29.3279991149902
1994-01-01	21.4720001220703
1995-01-01	18.7830009460449
1996-01-01	16.9009990692139
1997-01-01	16.6110000610352
1998-01-01	17.7140007019043
1999-01-01	18.5259990692139
2000-01-01	16.3409996032715
2001-01-01	15.7089996337891
2002-01-01	14.8850002288818
2003-01-01	15.3780002593994
2004-01-01	14.0970001220703
2005-01-01	15.9580001831055
2006-01-01	13.8590002059937
2007-01-01	10.1070003509521
2008-01-01	10.4940004348755
2009-01-01	13.6689996719360
2010-01-01	14.7069997787476
2011-01-01	15.7880001068115
2012-01-01	20.6459999084473
2013-01-01	21.6599998474121
2014-01-01	20.2399997711182
2015-01-01	16.2970008850098
2016-01-01	15.2580003738403
2017-01-01	11.3380002975464