Year	% of expense
1990	3.8713802452411716
1991	7.457689402445747
1992	10.203840859933146
1993	9.375481150734903
1994	6.457518432188554
1995	5.890313796786213
1996	5.620312702959534
1997	4.108887366621616
1998	2.891605250972144
1999	3.148313091113159
2000	14.775933479471732
2001	13.873264832311062
2002	12.855409317535415
2003	14.646178432497187
2004	15.100640281821839
2005	14.579799945910334
2006	15.732094766195875
2007	14.676661709500996
2008	14.291900070969643
2009	15.228548115797352
2010	14.372564763510029
2011	13.58950360183295
2012	14.305547399897064
2013	14.038795804634589
2014	14.104537030143916
2015	14.326715620939638
2016	13.996681610327203
2017	13.924716711220652
2018	13.124828528120961
2019	12.992128079122022
2020	12.406084207917354
2021	12.40198448036136
2022	13.95550723201852