Year	% of expense
1998	15.313751265048381
1999	15.041029995031849
2000	15.794368421867228
2001	14.880321485345227
2003	15.51839886213048
2004	16.44852107595589
2005	15.37567538344209
2006	16.968419705499453
2007	14.117268135835328
2008	12.268366898615717
2009	11.514663918599725
2010	11.297640537379461
2011	10.754741176638218
2012	11.288854365161244
2013	11.313514476877035
2014	11.329511624784228
2015	11.333768696150985
2016	10.433565283134836
2017	11.048165264645517
2018	11.356458168201705
2019	11.513940093399029
2020	11.323861442730902
2021	12.598474961188256
2022	12.343732067304543