Year	% of expense
2000	37.56243756243756
2001	32.80182720868138
2002	34.40881931109782
2003	30.412690203291753
2004	34.73997087427455
2005	33.33008871154708
2006	32.03345957351827
2007	35.76756968983118
2008	31.333074646397783
2009	30.64462335045131
2010	31.538693681432477
2011	30.941913384944534
2012	27.285678645990625
2013	27.633631111685343
2014	30.377225694283027
2015	23.297999401001707
2016	29.484173505275496
2017	29.635271977775783
2018	26.543867111877567
2019	23.820444686095644
2020	13.828586083616152