Year	% of expense
1997	9.52909234227659
1998	8.415433786945204
1999	7.533652366160132
2000	9.929430045104343
2001	10.335728589939922
2003	8.09973924380704
2004	17.574501225462125
2005	17.537979327650397
2006	18.962108038368765
2007	18.189115520546995
2008	19.476080347922213
2009	19.163393233890577
2010	20.018056141076528
2011	20.82096787323954
2012	21.280151390869577
2013	23.004761434844823
2014	20.631668580422918
2015	19.622049668523704
2016	19.37838468665788
2017	18.475977933278408
2018	17.939248101979118
2019	18.91022696010839
2020	18.1734585525128
2021	18.64989236813545
2022	16.085581580323964