Year	% of expense
2009	35.718456940675345
2010	36.13715633716545
2011	38.39500244231367
2012	40.05561415372425
2013	37.786358711275234
2014	37.352512354057325
2015	38.05588563328399
2016	38.49949081200009
2017	40.117481081287906
2018	37.110087539805406
2019	39.59130977327702
2020	37.1678236743041
2021	35.91687180177438