Year	% of expense
1998	29.45142506723154
1999	29.13134780536293
2000	30.469046806038396
2003	41.18776178588725
2008	40.35904894591047
2009	41.35578318319796
2010	41.80649648732646
2011	34.880784997729414
2012	51.22943525743641
2013	54.71217813435061
2014	58.82737649911132
2015	59.94229747050128
2016	48.55391225211251
2017	55.32858610215089
2018	55.77291083624224
2019	56.638083690010774
2020	58.599838906062296
2021	59.21259316665909
2022	58.06864092357519