Year	% of expense
1972	12.5
1973	21.875
1974	16.883116883116884
1975	14.175506268081003
1976	12.124711316397228
1977	11.656891495601172
1978	12.932297772567408
1979	11.519820417325647
1980	11.690680284515775
1981	10.182157870154134
1982	9.97728419989904
1983	11.565603483408763
1984	11.940792337831954
1985	12.335084248584486
1986	11.889053760986188
1987	12.397071389730444
1988	11.247262275995148
1989	10.50713097639523
1990	11.161292601926656
1991	11.343832299344255
1992	11.540533797148406
1993	11.497210589177993
1994	11.294573704159387
1995	10.935195647340167
1996	10.94837680869468
1997	10.84573328330101
1998	10.731490482225695
1999	8.79401034213517
2000	8.764637036775646
2001	8.955450028821609
2002	8.557085086813316
2003	8.138861894808468
2004	9.076127286219391
2005	8.384249830278344
2006	8.711419753086421
2007	9.18803884186841
2008	9.033271612081935
2009	9.007865992848926
2010	8.499469880114816
2011	8.51411320703718
2012	8.537954872869067
2013	8.723901134664134
2014	8.944094548801159
2015	8.955120971128805
2016	8.749431105923545
2017	8.758602648252598
2018	8.581978081527012
2019	8.479991425747977
2020	8.273659650252672
2021	6.485868614989256
2022	8.168807423239544