Year	% of expense
1974	17.771013814094978
1975	15.606162089752143
1976	14.908503767491913
1977	15.692509663773599
1978	15.30504336111811
1979	15.164414129244383
1980	17.058365010891364
1981	19.8169793909567
1982	19.37585510456707
1983	19.033075947908245
1984	18.821861710505555
1985	18.422461194102492
1986	15.279321333578139
1987	15.2130858728843
1988	15.172321301595233
1989	15.38582244158045
1990	13.631295188877846
1991	11.555312028251144
1992	12.665384277386634
1993	12.213109471156606
1994	13.768525052928707
1995	17.096455443211074
1996	17.112417771011412
1997	17.030372456186225
1998	16.629756342448747
1999	17.5382941471073
2000	15.735113893085973
2001	17.90003747895051
2002	17.155952596460253
2003	15.848880628821671
2004	15.719724590131879
2005	18.042203417234003
2006	17.251072654265865
2007	17.63079243227405
2008	16.646265253061788
2009	16.22990608286309
2010	14.35883323312106
2011	15.322592403157332
2012	15.36717893663296
2013	15.071313847957999
2014	15.1939989984831
2015	15.204851449609642
2016	15.540756168333804
2017	15.850040929696151
2018	15.956610297436496
2019	16.197871369301115
2020	15.318874799155275
2021	15.472229155833245
2022	15.444766552761351