Year	% of expense
1990	1.1877828054298643
1991	2.5381103458949164
1992	2.954068991804841
1993	3.8331272512230528
1994	4.499612102404965
1995	13.31916659775629
1996	11.358205559088347
1997	12.239429053830497
1998	15.923676982432253
1999	13.206254310832591
2000	13.78817952532051
2001	13.94709150396415
2002	16.247708388888483
2003	11.216855075311292
2004	10.156236887047996
2005	9.557436630372877
2006	10.49829363298627
2007	11.307066982424663
2008	9.378254194660116
2009	9.223711739879926
2010	9.348334888205043
2011	12.688610599051561
2012	9.994596638283433
2013	10.450044198733513
2014	11.674912528143429
2015	13.51019640980961
2016	14.146900179917271
2017	14.057623632308742
2018	13.756231977168031
2019	14.558074129198015
2020	19.97156888119917
2021	18.0552863364303
2022	18.765875164328634