Year	% of expense
1999	16.644965588290003
2000	16.677791532941892
2001	11.354368712624568
2002	9.121720176344297
2003	7.176574352665057
2004	5.05970683245881
2005	4.833047597237187
2006	3.2939607544294156
2007	1.8394320900498098
2008	1.749589324692275
2009	1.421279874163363
2010	1.5617605300520587
2011	1.9399284727070656
2012	2.034809627265114
2013	2.1203853221226128
2014	2.074101877771222
2015	2.6611711303856582
2016	2.521454077804972
2017	2.5061684269783506
2018	2.6911653308222467
2019	2.918011393827544
2020	2.3540439343996913