Year	% of expense
1991	43.823017648521024
1992	33.241109523375165
1993	34.83570195673562
1994	31.318181721324773
1995	38.8623435491912
1996	43.48383974437467
1997	44.9013647992838
1998	43.219151834354406
1999	42.381227799345616
2000	41.20126887729681
2001	42.97618875075959
2002	45.27112664979676
2003	43.136383434871846
2004	42.19178390630891
2005	42.486019334571175
2006	43.64678786211961
2007	41.773075960704375
2008	40.18276324945748
2009	40.87519293855333
2010	40.47379387561607
2011	39.23295236448917
2012	41.171135331199984
2013	40.44519413040067
2014	39.33593193063695
2015	40.765492270159136
2016	40.91150640085841
2017	40.956031477639
2018	41.25498932314408
2019	40.834673314651525
2020	43.68058612635937
2021	41.19178761152181
2022	58.771080111406235