Year	% of expense
1991	32.92319164802391
1992	43.581324171759206
1993	40.937760759993
1994	38.69119100607805
1995	9.942660293421364
1996	9.118349164144815
1997	10.107876507783569
1998	10.37383091347547
1999	11.274545838702176
2000	10.864266597709388
2001	9.322428593295252
2002	8.95563243717166
2003	8.052140872560084
2004	8.790630832463737
2005	9.287254223131255
2006	9.8413467361027
2007	11.338058589008481
2008	11.387821720223624
2009	10.365250600910517
2010	10.538429192306872
2011	10.416168913282583
2012	11.019328361783124
2013	11.313514476877035
2014	11.354356658720398
2015	11.181051317243565
2016	11.386699452428516
2017	11.46553490036152
2018	11.356458168201705
2019	11.513940093399029
2020	10.5132603707104
2021	11.01506925715714
2022	10.75678173290239