Year	% of expense
1990	35.15847540495727
1991	30.534901536659003
1992	29.047976011994002
1993	30.37701429005777
1994	31.0325122560077
1995	31.612758646448047
1996	28.868939215392196
2006	32.53635054981201
2007	33.32284172216828
2008	32.9877127531016
2009	31.033624410884396
2010	27.59653466378815
2011	28.721527784320905
2012	30.402820381604222
2013	30.716507148604737
2014	32.18179692283657
2015	28.445021024275125
2016	27.49549372778232
2017	27.0032398133223
2018	27.756287800213226
2019	20.33011095403041
2020	22.155605349714744
2021	22.472613569897327
2022	22.394540362606964