Year	% of expense
1985	35.254562920268974
1986	36.74549947052594
1987	33.86120167675827
1988	28.739642389882253
1989	29.582309582309584
1993	29.106797748088397
1994	29.174548581255372
1995	24.04516185939843
1996	20.31711487641847
1997	23.31085826661048
1998	24.552603036876356
1999	20.66143649398079
2000	24.55943502079071
2005	29.623939982654964
2006	27.079599367422247
2007	26.65090325871019
2008	27.913447808074725
2009	40.96944247876867
2010	39.677892218583146
2011	46.1154225558514
2012	46.72333309510215
2013	36.66094525237938
2014	34.86791187960823
2015	20.378923487730862
2016	31.783959114899712
2017	37.564149018412756
2018	30.60570609574973
2019	31.46417477788112
2020	24.33898549955443