Year	% of expense
1990	8.162921111439053
1991	25.766386973498378
1992	31.600853980157517
1993	25.697938529656994
1994	12.324226875606712
1995	21.778880513491284
1996	18.219055657613822
2004	15.509732845488426
2005	16.117998458376157
2006	16.57401299721233
2007	17.818298577511683
2008	15.46370317363443
2009	15.767065057992923
2010	12.875283459979444
2011	14.43192452656177
2012	15.225472780051868
2013	15.465175946838666
2014	12.331201581464683
2015	12.04582020415111
2016	12.490987284816587
2017	13.510784952866203
2018	17.935027271112062
2019	15.45853464674884
2020	14.857141739266932
2021	14.334039869609313