Year	% of expense
1999	20.67907981263796
2000	23.966107947317578
2001	32.85602841405347
2002	37.759586623882065
2003	36.620197014283676
2004	52.69790004186695
2005	36.49617850815038
2006	38.69567876349957
2007	34.95640162306829
2008	36.5096325185758
2009	46.747196343821415
2010	36.13715633716545
2011	31.324935552746773
2012	35.93920599428617
2013	31.025385456489555
2014	32.92312166080226
2015	47.860634158118586
2016	48.20072413680323
2017	44.614946873681774
2018	38.468450191137606
2019	39.50388510733903