Year	% of expense
1972	8.69231261601485
1973	7.953667953667953
1974	7.798185838711133
1975	7.268679451626762
1976	6.710001375705049
1977	6.415418124216224
1978	6.483991737671056
1979	6.508457925275534
1980	6.451518606214739
1981	6.784802948681599
1982	6.5992835209826
1983	6.565521921427013
1984	6.401028857652129
1990	7.406271557191328
1991	7.132937110571805
1992	7.151399637609673
1993	6.706960190454654
1994	6.62898324315704
1995	6.5093358634995155
1996	6.326209660438279
1997	5.98554178604424
1998	5.80564984211693
1999	5.553001078368994
2000	5.876064179203203
2001	6.416856428756564
2002	6.087422833418792
2003	6.557497524564808
2004	6.58402413418469
2005	6.428641522429084
2006	6.401367529242051
2007	6.518943475852944
2008	6.600906524350276
2009	6.727940285632959
2010	6.79609817196047
2011	6.792313788792066
2012	6.944058012765026
2013	6.9458935792891126
2014	7.070948121441104
2015	7.061257783221847
2016	6.936116193727076
2017	6.996156110761596
2018	6.997150400898816
2019	7.086729839604414
2020	6.317114097679593
2021	6.344785380315346
2022	6.995867675315652