Year	% of expense
1999	20.121028156032466
2000	18.583233977350012
2001	12.161566975891443
2002	11.717885182391905
2003	19.018580144899328
2004	12.32389642871758
2005	21.889842893545115
2006	22.23226754061573
2007	27.552199841913914
2008	19.15535483071647
2009	19.52734398495342
2010	30.49062549091075
2011	32.03439862843391
2012	23.382884068817084
2013	24.814047250907393
2014	26.670298607740012
2015	19.468708678789678
2016	16.03909069694396
2017	11.30288147442255
2018	11.348316564381621
2019	10.58105077159576