Year	% of expense
1999	11.309532135114344
2000	9.059949850995379
2001	9.06089909045924
2002	9.714096777819906
2003	7.816793030411616
2004	9.065206266960073
2010	7.286525874543323
2011	7.261910803970646
2012	7.258544791485881
2013	7.806391854019032
2014	7.028846750315567
2015	6.869785907072499
2016	6.022305829736863
2017	4.676837246160222
2018	6.288669111736269
2019	5.846072274406854
2020	6.353194545848065
2021	5.815509711048753