Year	% of expense
1990	57.820037754317276
1991	57.71989846595299
1992	61.428583818287464
1993	57.407614529271044
1994	52.39349586253116
1995	51.74349460063746
1996	54.17197348225075
1997	46.22884135940165
1998	43.21781800615291
1999	37.60132830635652
2000	42.03065285622351
2001	47.02698676092083
2002	48.12031472263571
2003	49.14079291075621
2004	51.87123786153233
2005	52.9155165808947
2006	56.250086920725515
2007	56.18456341224406
2008	57.592378085434994
2009	59.14383546898143
2010	61.685756587178005
2011	60.08032116321479
2012	58.33247363980286
2013	60.42846415434043
2014	59.96539226325842
2015	61.01272839654172
2016	60.11099476094166
2017	60.647536849976014
2018	55.13579401132981
2019	55.50909349124049
2020	56.708143599735294
2021	56.475340773108904
2022	57.665672663599075