Year	% of expense
1990	54.97242821829245
1991	53.72722252898951
1992	52.63251511917467
1993	55.93692022263451
1994	57.475380483437775
1995	54.93619879113499
1996	50.64501441796935
1997	51.56804804399724
1998	52.463422733043
1999	47.83721809247827
2000	42.54537774559498
2001	42.929642445213375
2002	43.405223799718215
2003	42.172172172172175
2004	44.07013826536257
2005	42.079869956658186
2006	43.3027620414517
2007	42.587625462648475
2008	41.0421982715036
2009	40.30912281565519
2010	48.006217865847546
2011	44.40313942824767
2012	44.30324978891143
2013	43.95102513797186
2014	45.000321812890995
2015	34.70248468655393
2016	32.24520194604361
2017	29.566855838829824
2018	32.69595355906147
2019	29.038069754935915
2020	28.41117689501229
2021	23.607083791536045
2022	23.799548016953427