Year	% of expense
1999	12.710563485363524
2000	13.85627966361509
2001	12.159162593813193
2002	16.91799006834161
2003	18.01416184778228
2004	17.72186532356154
2005	19.2077012527972
2006	19.725662030863024
2007	16.713077355505877
2008	18.152973739283063
2009	15.912556377702519
2010	16.162643950149867
2011	16.0608694413177
2012	17.352623466155283
2013	18.174174508602928
2014	16.541499675791783
2015	13.736497846132991
2016	13.107568785288926
2017	12.883658466359918
2018	13.150948889297823
2019	13.1226869860512
2020	11.926214783346438