Year	Percent
1991-01-01	18.5578210402562
1992-01-01	19.4236186744211
1993-01-01	22.9997933425425
1994-01-01	25.0098349435294
1995-01-01	24.5860633873817
1996-01-01	25.1771470067054
1997-01-01	24.7867898136888
1998-01-01	22.9282885241757
1999-01-01	21.7058220633695
2000-01-01	19.2505711846409
2001-01-01	17.2405361781367
2002-01-01	17.5899122698043
2003-01-01	17.9444185564197
2004-01-01	18.5840131106252
2005-01-01	18.6818180228264
2006-01-01	17.4678551143364
2007-01-01	15.8875985459208
2008-01-01	16.4053911554215
2009-01-01	21.2564324682909
2010-01-01	22.3823686706007
2011-01-01	23.1407755842465
2012-01-01	25.7882118904862
2013-01-01	27.0879305485540
2014-01-01	26.7534897926578
2015-01-01	25.2863831140042
2016-01-01	23.8702199355660
2017-01-01	21.5563823297114