Year	% of expense
1972	35.650118203309695
1973	38.33661417322835
1974	37.38656987295826
1975	39.06542056074767
1976	37.754800590841946
2003	13.441040311396662
2004	13.093836787265154
2005	15.800163692553632
2006	17.151400412727593
2007	16.685667227070073
2008	15.696467392581903
2009	16.722478185098556
2010	13.997320862024395
2011	14.070697188265575
2012	15.382494065479682
2013	16.618670494056868
2014	14.184788477448821
2015	17.791852118799138
2020	16.06167966186642