Year	% of expense
2001	29.041026785743878
2002	29.501155788932966
2003	29.624425384189877
2004	34.86744746522346
2005	36.98557460428816
2006	36.174789915966386
2007	40.229309836373226
2008	37.51683501683502
2009	44.98571414299843
2010	41.85329520822764
2012	40.773539921304284
2013	42.910303811160475
2014	44.57184878527073
2015	41.692554695716986
2016	33.4260600755359
2017	38.24251699469694
2018	33.43957147111552
2019	33.88551451841561