Year	% of expense
1990	2.7804940266145146
1991	2.735343157135776
1992	2.548725637181409
1993	2.3928245667376102
1994	2.5414298174381185
1995	2.2808197007046638
1996	1.9583056585177727
2006	1.3883534406430567
2007	1.2294980555877233
2008	1.0770288695511399
2009	1.3039080219854222
2010	1.8194822291698234
2011	1.9057666196969396
2012	2.0063093140307893
2013	1.9450848178868467
2014	1.7345845809595168
2015	1.9307769465115816
2016	1.99356983285517
2017	2.1089797241523063
2018	2.160528696223031
2019	2.324084779188328
2020	2.046923652089669
2021	1.9718805766620102
2022	2.560957066494539