Year	% of expense
1990	29.531770132214675
1991	34.79948971102113
1992	31.084793009854344
1993	36.39739891324458
1994	17.498780158857116
1995	18.525815820721732
1996	36.18361908110548
1997	31.396761322271942
1998	12.081729975996211
1999	28.738592961330962
2000	37.15625543744118
2001	36.62421588235252
2002	35.21340066388211
2014	19.871082999372312
2015	21.456717315623298
2016	20.87478037539281
2017	25.948688340089298
2018	26.348628835112713
2019	31.95044125898766
2020	24.776215215369948
2021	26.303517109045103
2022	27.89735987363115