Year	% of expense
2003	32.811468433441576
2004	28.525832768150202
2006	33.524505668701885
2007	35.039646933727056
2008	34.630748603875105
2009	36.00843844767723
2010	36.70542382988937
2011	36.629838792320996
2012	35.75233719112129
2013	37.10443392459204
2014	34.77802907535599
2015	36.407070881239285
2016	35.404104569172304
2017	36.153413553687315
2018	35.940320407041824
2019	36.012749366136426
2020	33.053586937721875
2021	34.1193494506676