Year	% of expense
1972	2.932551319648094
1973	3.0465021137324424
1974	3.323689224472514
1975	2.7669649664914324
1976	4.466383812010443
1977	5.100368993175763
1978	5.702907991445638
1979	6.7691591478418935
1980	7.528682528682529
1981	7.08556935661317
1982	6.531080346437694
1983	6.880980539726911
1984	6.923784080602669
1985	7.519009525963197
1986	9.03442434202184
1987	8.548363780921921
1988	6.840477536496957
1989	6.855753833392855
1990	6.534737343256622
1991	5.695092979438027
1992	5.559751620472119
1993	6.0949481449962395
1994	6.122318525599491
1995	5.746079420960634
1996	5.450238839867946
1997	4.879794406281917
1998	4.534778767629997
1999	3.8922749120459836
2000	4.030708183112987
2001	4.6078185691016165
2002	3.7895235127546285
2003	4.344896826864646
2004	3.894962595415004
2005	4.345802934871122
2006	6.691264948429058
2007	6.874482831666258
2008	5.3092966151742145
2009	3.0614666103372246
2010	2.4690757601046083
2011	2.118391427618412
2012	1.4848488763749015
2013	1.3476068621958421
2014	1.2075942980586112
2015	1.1436916504145442
2016	0.9321083965668174
2017	0.7913751309431876
2018	0.8848877794218973
2019	0.8402700976313827
2020	0.7042836176731528
2021	0.5595516503864625
2022	0.9162639836626604