Year	% of expense
2001	26.804357694053564
2002	21.343733380606274
2003	30.268150124988324
2004	16.96096298697989
2005	16.945284512305584
2006	17.448232682261946
2007	17.732063639231747
2008	29.399980129710237
2009	26.498666259112845
2010	24.604832303744807
2011	26.33646004866055
2012	22.519240551654583
2013	27.400837987987924
2014	27.257677871426587
2015	31.031771039960383
2016	32.596666336049616
2017	33.84097756710104
2018	25.762636858503967
2019	24.916683546223926
2020	28.572617642638278
2021	25.9007351106639