Year	% of expense
2000	21.430263338333866
2001	21.538711310915858
2002	22.18971205923604
2003	21.257490523318324
2004	23.11977619193069
2005	22.04513456159511
2006	20.980775894689163
2007	19.72183674698874
2008	21.103590609375793
2009	18.32200379481119
2010	14.174517070071396
2011	15.01415514598031
2012	14.410455353327514
2013	13.455649737185762
2014	14.53105657188894
2015	14.283486059660753
2016	12.482754600392514
2017	13.864196873724739