Year	% of expense
2001	25.84633078992622
2002	26.911999785638834
2003	29.427065693035104
2004	25.968585991060205
2006	26.410261970181043
2007	26.00557187024539
2008	27.187508552447355
2009	27.34999209842823
2010	29.206010646150887
2011	24.905850712841158
2012	25.135105843690056
2013	21.158717521900094
2014	18.01006953124049
2015	18.660597471165413
2016	21.99441893228591
2017	21.823904883599397
2018	24.35710850400028
2019	22.017647230850162
2020	17.512840094140564
2021	18.876486165275356
2022	20.849043039933672