Year	% of expense
2002	37.2693201896987
2003	35.69558415509746
2004	36.47831112062395
2005	36.37079457789408
2006	33.0296914244831
2007	36.82137944641063
2008	38.88350741878831
2009	37.875261703450605
2010	35.747390803590015
2011	33.40393767040531
2012	34.27879656266119
2013	37.75544372859167
2014	39.45339657773546
2015	44.435680458493465
2016	45.77552847162288
2017	46.696420562130264
2018	48.39136430108641
2019	45.3553180849438
2020	45.329781367064705
2021	37.84473840383423