Year	% of expense
2000	19.634339503465814
2001	19.623701618332273
2002	20.077243904880117
2003	22.24204369312632
2004	22.51982643073381
2005	20.056185879161788
2006	22.943999455432937
2007	23.492042884635833
2008	29.183036656371286
2009	28.17374112780967
2010	32.291656610105996
2011	36.279573554921356
2012	36.173827665476495
2013	35.795451907904685
2014	34.99885657807788
2015	35.29706296717186
2016	29.52924582533385
2017	34.03122685570049
2018	31.90515618867765
2019	28.060107710743758
2020	32.45526473879163
2021	30.923463366763038
2022	31.506424533873854