Year	% of expense
2004	28.215429243301987
2006	28.783034843847105
2007	27.504217228968436
2008	29.399980129710237
2009	27.69080716672814
2010	27.72967960252965
2011	26.986030648629676
2012	27.88075878054714
2013	26.900218833756433
2014	27.257677871426587
2015	28.69934095657497
2016	30.09902956938302
2017	30.330965672447306
2018	26.777301033068554
2019	28.99449881027632
2020	28.64772243607015
2021	26.419549786447945