Year	% of expense
1999	16.912961589923214
2000	21.521268426987277
2001	13.942042364550536
2002	13.830092559374327
2003	12.560757980932577
2004	13.47301379100121
2005	12.670510833947215
2006	13.549584675610868
2007	11.944956634625242
2008	13.366749697812597
2009	11.570937293728022
2010	10.391730747981216
2011	12.485117832275938
2012	10.341961108568222
2013	9.412979537057248
2014	10.627737509346147
2015	10.666626637045127
2016	12.015334009953843
2017	11.016478057136341
2018	8.343941360291833
2019	8.202060165427062
2020	6.039426759141834
2021	5.537312226518535