Year	% of expense
2001	47.40415914263219
2002	46.02209293943693
2003	42.41566407171503
2004	43.55598116670657
2005	42.22438731919358
2006	45.75731697849546
2007	43.635868083946576
2008	42.492089079945075
2009	44.611846990347075
2010	43.582002602479434
2011	43.316563560648
2012	44.542647184971266
2013	49.535825144115925
2014	53.237913819056324
2015	33.396344351802185
2016	33.27638225056986
2017	30.330965672447306
2018	30.97388367221006
2019	32.37619236626405
2020	28.722827229502023
2021	25.628402366342474
2022	22.45544662234378