Year	% of expense
1991	8.45988867673412
1993	12.309013651568575
1994	15.466741054446786
1995	17.88859224552359
1996	17.150891452906148
1997	17.008467796066483
1998	18.584854596476262
1999	18.706642434260814
2000	17.760725965036592
2001	18.047584129560416
2002	18.0139139882285
2003	17.354925106636244
2004	17.421699772779814
2005	18.042203417234003
2006	17.251072654265865
2007	17.63079243227405
2008	16.646265253061788
2009	16.22990608286309
2010	14.174622567306077
2011	14.1192344761118
2012	15.214151246205112
2013	15.598979496310076
2014	15.965212870255682
2015	16.059609722660547
2016	16.671327050712133
2017	16.696961949578174
2018	16.36976438766138
2019	16.598991029382816
2020	15.986406251202762
2021	15.950629803146036
2022	15.946248715828448