Year	% of expense
1997	2.967134652201659
1998	4.756706175920149
1999	7.487236869711168
2000	9.827238417842008
2001	8.414607284848078
2002	8.00134080874172
2003	5.361336676557025
2004	4.131059858920216
2010	2.3615950911933017
2011	2.594923423610865
2012	2.3486278271640284
2013	2.94591543656814
2014	3.3184031249070474
2015	4.073929534907986
2016	6.820781807556731
2017	3.968997728944882
2018	6.438129693370123
2019	6.063339696804548
2020	6.40751639055593
2021	6.79834849936599