Year	% of expense
1972	7.450980392156863
1973	6.630525437864887
1974	7.829817661780479
1975	6.987143655673561
1976	8.165829145728644
1977	7.7596741344195515
1978	6.802047218094766
1979	6.5962307252998285
1980	7.055469770756622
1981	7.719100065894757
1982	8.379165318667098
1983	7.751995270469997
1984	8.215826411692744
1985	8.160339488473449
1986	8.818788855629748
1987	10.467199044704829
1988	8.725076408091981
2001	31.495211805871907
2002	27.397197347007186
2003	27.7828820034049
2004	26.461168862814855
2005	27.828537652519454
2006	29.264226437462952
2007	30.250821242814123
2008	28.62938987578604
2009	11.66940940118429
2010	11.595735877961731
2011	9.83111387368478
2012	11.061623127405774
2013	11.202731913289506
2014	11.637706978467746
2015	11.587571201562174
2016	11.795856190660995
2017	12.065512620471482
2018	12.168344912714273
2019	12.51735320581895
2020	10.890394454935464
2021	12.061315675923998
2022	13.89301458777883