Year	% of expense
1996	34.335723323492196
1997	27.559630728100586
1998	29.36519602696289
1999	25.827459119046768
2000	27.794581441505123
2001	26.39187683964303
2002	29.88587205267898
2003	29.427065693035104
2004	26.558922408497427
2005	26.61403563516086
2006	26.972124414576665
2007	27.03167481084391
2008	27.220115884308328
2009	27.69080716672814
2010	31.157808063893704
2011	27.871236939909316
2012	29.453081263337044
2013	29.06810711796236
2014	30.73981680622101
2015	32.53987980322139
2016	34.897048241713364
2017	35.471433111370054
2018	34.700395846233775
2019	30.67125517223048
2020	31.675842377643846
2021	32.1289438920428
2022	27.32995246233878