Year	% of expense
1991	7.547512407698825
1993	24.08010125666757
1994	27.388228133796567
1995	22.63961741725086
1996	22.27961172925675
1997	16.846895478191012
1998	18.292978816842947
1999	16.24755357603251
2000	18.746790098806024
2001	13.271548517464298
2002	15.221764124845883
2003	15.001214066116747
2004	11.151955661577304
2005	11.809178159446642
2006	12.187096833604517
2007	10.675135354873003
2008	10.708612736727368
2009	8.352093100020248
2010	9.430486541656993
2011	7.986139989026254
2012	8.78652853397976
2013	8.417837488435264
2014	8.36865795610828
2015	8.813036707542848
2016	8.269281333365827
2017	8.077774717333945
2018	7.490558159091791
2019	7.27410371748828
2020	6.280756192337648
2021	6.2577223114605385
2022	6.9045802530292715