Year	% of expense
1972	41.285140562249
1973	38.429464906184855
1974	40.29498525073746
1975	40
1976	39.71600688468158
1977	38.22652757078986
1978	39.77272727272727
1979	39.52132555998772
1980	36.8819374369324
1981	35.85532386049087
1982	37.0929597962525
1983	36.86137195607194
1984	35.204081632653065
1985	41.43947655398037
1986	29.767943874797627
1987	22.991869918699187
1988	31.568047337278106
1989	31.509013194573498
1990	31.421446384039903
1991	28.122774533542234
1992	29.55079376379298
1993	31.12870454704687
1994	43.982423305395066
1995	38.65534896254379
1996	29.045926735921267
1997	34.221564273377744
1998	30.59360730593607
1999	32.3952788706318
2000	29.325445605408728
2001	27.377531472359056
2002	30.961013718087692
2003	30.635880790793745
2004	31.11174641746775
2005	34.00522583053378
2006	28.276309388681693
2007	32.13703591910655
2008	27.154901220586385
2009	27.009177030128328
2010	30.393422589276476
2011	27.174847924418994
2012	28.7189829291151
2013	29.625648239517943
2014	28.65537425260979
2015	23.83870857720762
2016	26.604852119885088
2017	26.504003893288502
2018	24.83360345245369
2019	24.451368521729165
2020	14.285335616496738
2021	20.66638450988119
2022	20.083375772051575