Year	% of expense
1990	16.731547675081817
1991	18.13645427308891
1992	15.389673247977207
1993	14.735913166185629
2000	13.778572252732586
2001	13.35635665101769
2002	11.804286626196175
2003	10.2108579013535
2004	10.32731877488273
2005	8.677006552006553
2006	10.47345812659278
2007	6.411929990927269
2008	12.684914016240057
2009	15.401587143822896
2010	14.045171307126477
2011	14.66815486713728
2012	17.136516242716308
2013	17.773979918820764
2014	18.232031148037628
2015	21.466322693801356
2016	20.650468407689303
2017	20.647566887899682
2018	20.247146421484842
2019	19.78538968741917
2020	25.206598346428354
2021	23.768237344288437
2022	21.455180411132392