Year	% of expense
1982	61.87793427230047
1983	62.15626364033173
1984	68.772386844676
1988	45.14742748000478
1989	39.97817785051828
1990	43.11926605504588
1991	41.8508905396939
1992	45.17710710964579
1993	46.36006289308176
1994	39.346840036286665
1995	40.13931654131543
1996	37.15792692248891
1997	42.309314721785476
1998	46.884
1999	45.52165655823072
2000	46.48091905453585
2001	44.699607704853
2002	44.772976999797805
2003	38.95614288944576
2004	44.121559203504965
2005	44.56935773955092
2006	44.436143485417546
2007	43.69184683849394
2008	35.219784756819244
2009	32.664418886682576
2010	37.01756836661907
2011	39.30278197256531
2012	35.66536586257431
2013	32.97272314604529
2014	31.797961694706323
2015	25.802597160204066
2016	25.43385930909142
2017	25.930402590124267
2018	22.56034134811701
2019	25.022483713938115
2020	18.97177359346753