Year	% of expense
2002	37.704375101918146
2003	36.26443226893706
2004	36.47831112062395
2005	36.37079457789408
2006	34.14035184414965
2007	35.039646933727056
2008	36.15647839704627
2009	38.909011106056006
2010	36.13715633716545
2011	36.42937746660226
2012	35.93920599428617
2013	36.608213947911516
2014	35.94035508263879
2015	36.23244627596517
2016	35.268308476140334
2017	35.86783342347407
2018	36.10657945312995
2019	35.48426875309947
2020	33.953778607766225
2021	33.16674290564538