Year	% of expense
1999	10.925348997598041
2000	10.26913104786742
2001	23.289939698462476
2002	24.5069847279792
2003	24.593651695328536
2004	24.521517841472765
2005	23.21458644810779
2006	25.984723630766236
2007	26.533239995995224
2008	19.484380289941335
2009	21.18663460386647
2010	23.280114798407144
2011	21.968339589704655
2012	25.672700695439044
2013	26.698872557342323
2014	27.81810683499068
2015	26.11413314571227
2016	25.150566423840655
2017	26.68167366075682
2018	20.992553474219942
2019	23.017144137958898
2020	22.435550050321282
2021	20.315437166560223