Year	% of expense
1990	61.87577934801981
1991	63.121440145340266
1992	62.39004423653829
1993	63.60184431787361
1994	62.957122415408506
1995	52.9245815309385
1996	54.333030852994554
1997	53.16014078099802
1998	51.40397097567079
1999	53.679227877065465
2000	53.4190745785631
2001	54.190003019406554
2002	53.77586964771078
2003	54.057943526862964
2004	52.96948141941631
2005	53.132377023897476
2006	53.49051181390176
2007	56.46391600886338
2008	52.80332405219387
2009	55.14407707425942
2010	52.317875897384255
2011	51.81696794530504
2012	53.938383879230386
2013	54.44981966468717
2014	55.77393315084837
2015	56.713277629936876
2016	53.85704142019694
2017	54.98390595381707
2018	55.1509023923372
2019	56.58892333385187
2020	57.64842758738921
2021	61.12279866983755
2022	57.440815621310676