Year	% of expense
2000	20.389445769920826
2001	18.88216354798726
2002	15.948566059419322
2003	19.175416374652528
2004	19.47673741458635
2005	18.954660009425453
2006	21.50568060171073
2007	21.449048849449625
2008	21.211821128885845
2009	20.40150652261211
2010	20.56343828716835
2011	19.030127108555277
2012	19.351450510992503
2013	19.82738698669633
2014	19.20692869526043
2015	19.010721686638433
2016	18.069266430324515
2017	19.51109146777792