Year	% of expense
2008	33.45318588826217
2009	32.350823014260186
2010	31.10656772383195
2011	29.493719053545007
2012	29.593543949917343
2013	28.830520248577812
2014	28.813896225333412
2015	32.93023893847331
2016	32.44869685932222
2017	30.64971766759537
2018	29.713398518933307
2019	32.37619236626405
2020	31.675842377643846
2021	27.76073783038055