Year	% of expense
1973	11.072555205047319
1974	5.816345614363194
1975	4.714226115978306
1976	4.920072748157366
1977	5.638895299638434
1978	7.560849300880373
1979	9.458034584563475
1980	15.315144924109886
1981	17.620775253007448
1982	21.108335524585854
1983	21.755215914604562
1984	22.539828607580375
1985	23.373278671291917
1986	23.21827663272908
1987	20.251577859389087
1988	15.535884660235343
1989	13.605221237569404
1990	17.878342245989305
1991	18.711043583332337
1992	15.422227818349702
1993	11.703738900602858
1994	11.037614029241471
1995	12.479515470068042
1996	13.11126765287981
1997	13.165634763501528
1998	13.871232314947715
1999	12.586439534491484
2000	12.250457410042692
2001	12.790386686972996
2002	12.193320610028403
2003	13.921474554958719
2004	13.936516214027913
2005	12.1014684310646
2006	11.786493224136706
2007	14.601417638296779
2008	15.547869985116522
2009	13.193180126641705
2010	10.968877982164162
2011	9.454871612405858
2012	9.26151121771073
2013	7.795524447410315
2014	7.797990849185514
2015	10.162471069835481
2016	9.807254328486813
2017	7.510394311774306
2018	7.271651597331965
2019	7.964362305424279
2020	7.189579362196798
2021	6.3296264194514285
2022	6.8995884603096