Year	% of expense
1999	20.383243583467376
2000	25.298143862522167
2001	30.540919509936803
2002	27.68445837443879
2003	25.572484854258406
2004	24.568781185715928
2010	22.117715685696044
2011	23.50353633983284
2012	25.54409650015337
2013	19.03894555525357
2014	19.423638535754733
2015	23.359479626545838
2016	25.545200053104523
2017	42.217681049906886
2018	18.49749166428071
2019	19.99656140381768
2020	18.34866541835146
2021	14.829508690020408