Year	% of expense
1983	38.15198932557011
1984	36.967274400414105
1985	35.1492694207926
1986	35.624534392848275
1987	36.10714050095661
1988	39.67631365065903
1989	44.587760404584046
1990	44.75668449197861
1991	24.804984333235062
1992	40.3393351800554
1993	40.38547203991328
1994	45.190152872078976
1995	32.35206141823102
1996	30.626295604601992
1997	29.671662948415985
1998	29.409386618033714
1999	37.76353516613257
2000	38.24354543606424
2001	37.0948330299766
2002	38.25343304907216
2003	36.713160601087225
2004	37.21064579128551
2005	36.8423501196999
2006	35.69320776471535
2007	35.41206533463455
2008	34.279661627588595
2009	35.718456940675345
2010	34.95381794030913
2011	35.394001714659154
2012	34.805241893279614
2013	32.2678643916875
2014	31.60182858436016
2015	32.153552343036594
2016	32.640943686106326
2017	33.4630735393049
2018	30.8690111800315
2019	31.94790845091201
2020	28.991904131518787
2021	26.89995162468824
2022	22.330457361810794