Year	% of expense
2003	14.26380679637222
2004	13.47301379100121
2006	15.855919655888894
2007	15.370866845397677
2008	14.308962662163328
2009	14.701925388125826
2010	14.373548347626151
2011	14.39840260761393
2012	15.98100172727178
2013	15.600676544518047
2014	15.266963467256192
2015	15.713842365602865
2016	13.900288547819711
2017	14.623406094661767
2018	13.913573999226504
2019	13.533507980508453
2020	13.502798432651945
2021	14.829508690020408