Year	% of expense
2006	20.890171388597413
2007	24.451277750599857
2008	15.324301766348306
2009	20.463701794273963
2010	17.141807253307977
2011	15.945781435143077
2012	12.241107585111836
2013	12.5600823680975
2014	14.740228485369725
2015	17.350295260790944
2016	20.31463674387421
2017	20.360489288940865
2018	23.383182244600285
2019	24.934205793978805
2020	27.96426529504791
2021	27.76073783038055
2022	21.701093541526202