Year	% of expense
1980	11.533720830638575
1981	12.837003825320696
1982	11.673474494648362
1983	13.062486169990997
1984	12.813502198836247
1986	11.319684749602484
1987	12.098550707626067
1988	12.818019915552686
1990	11.924399106624005
1991	10.514304985666936
1992	11.93796641630189
1993	13.07857335499886
1994	12.475440609063138
1995	9.645542183803151
1996	9.118349164144815
1997	9.897443912492095
1998	10.37383091347547
1999	9.113645905212618
2000	9.80991022013285
2001	9.54239530970857
2002	9.606424010793623
2003	9.471873074586782
2004	9.444078922046863
2005	9.662734485029942
2006	10.306220609477865
2007	10.420972975768503
2008	10.193687217895896
2009	9.860751271252798
2010	9.770116320332924
2011	9.326612626185387
2012	9.193992220054078
2013	8.651543146426041
2014	8.790422980659882
2015	8.884078839335826
2016	8.8683430933577
2017	8.682472079223736
2018	8.824094718689455
2019	8.768851879384494
2020	8.273659650252672
2021	8.308108036453275
2022	8.794942074583377