Year	% of expense
1972	20.702068289773575
1973	21.292432389053847
1974	20.251532277322294
1975	20.46012057376481
1976	18.79836083839897
1977	17.943280334911933
1978	17.014307877952078
1979	16.006212813516978
1980	13.784233515912083
1981	13.617906781227454
1982	13.3075236954801
1983	12.947942714253239
1984	12.451715708767509
1985	12.511704355024737
1986	12.509834461550751
1987	12.960148469481272
1988	13.117403489993382
1989	12.784436280987368
1990	12.401212925234532
1991	12.023715997250319
1992	11.69279385518512
1993	11.530379828050814
1994	11.322565247821775
1995	10.305847274683542
1996	10.33602102317572
1997	10.414272593762618
1998	10.527727660163636
1999	11.086777182088822
2000	10.90152719288184
2001	10.989234125909764
2002	11.196008531029491
2003	10.893484593669289
2004	10.703095829477752
2005	10.700516344899604
2006	11.024089704003979
2007	11.423514498242033
2008	11.438334858464781
2009	11.138461708855502
2010	11.043787143038175
2011	10.80960587011202
2012	10.453153890454972
2013	10.931712615372295
2014	10.856867897990155
2015	10.827501129205379
2016	11.043899472593266
2017	11.071573297071861
2018	11.275083778402959
2019	11.573041010420502
2020	10.528825629734072
2021	10.907385504579606
2022	11.411060313165553