Year	% of expense
1972	20.54239784022575
1973	28.560504683616916
1974	27.11962414166968
1975	26.073151370824988
1976	29.94327206716581
1977	28.030890884233095
1980	18.369118583251375
1981	17.110179401614342
1982	12.802844172537808
1983	17.672185902869256
1984	17.29389992254434
1985	16.125412952689633
1986	17.34787767258285
1987	16.764172142478053
1988	17.103680669173215
1989	15.293821179186681
1990	11.389669859120636
1995	34.4556169040727
1996	34.32019668607798
1997	9.687011317200621
1998	9.820956361256803
1999	10.773112618483992
2000	10.17948007225656
2001	11.872866136725573
2002	11.154018937862563
2003	11.494236066375112
2004	12.141157010975467
2005	10.978370121147474
2006	12.044194704719096
2007	12.620730718201093
2008	10.602140138220857
2009	10.31847282658545
2010	9.407610128396684
2011	7.158964411328737
2012	7.106033084610797
2013	5.857280614446308
2014	7.625472247886998
2015	7.286476890412505
2016	8.198498860031117
2017	8.204428958752699
2018	6.9726929519380185
2019	7.211052332264795
2020	6.725286262354913
2021	7.472676686438239
2022	7.9034873974612205