Year	% of expense
1990	4.944772668892885
1995	2.6811970247362047
1996	2.4841845394229285
1997	2.272727272727273
1998	2.5152319950007813
1999	3.7947457366722994
2009	2.3945147679324896
2010	2.207308275254982
2011	2.9939736274151922
2012	2.949461201288192
2013	3.5362948265304626
2014	3.3200684639466105
2015	3.6535648931038276
2016	4.194483255227514
2017	3.7941344520714133
2018	3.7156535737003233
2019	3.148540875353143
2020	2.41534938153393
2021	2.540806379185114