Year	% of expense
1990	19.865026805424158
1991	18.933970606813492
1992	20.388892157439546
1993	22.762610105613742
1994	20.826553162461185
1995	20.144611407335596
1996	19.98029700441493
1997	21.979297858942065
1998	24.318139761602794
1999	24.94140907967513
2000	23.70829499782093
2001	23.289939698462476
2002	24.5069847279792
2003	24.593651695328536
2004	24.521517841472765
2005	27.98008732989747
2006	28.164302357015046
2007	29.851869714486433
2008	28.214088044079865
2009	26.76423251999949
2010	27.811642910283414
2011	27.386312028174565
2012	25.672700695439044
2013	27.948967625004446
2014	28.813896225333412
2015	28.419370387447092
2016	28.728515179845402
2017	26.68167366075682
2018	26.67981757192226
2019	27.07615050697263
2020	26.617344048806334
2021	27.48958327670194
2022	25.2415902721903