Year	% of expense
1998	9.689742201618007
1999	9.108395635041676
2000	8.868425512682899
2001	6.869173785134512
2002	11.280749707145645
2003	11.318619128466327
2004	13.370473537604457
2005	12.47383286260176
2006	14.234194246400534
2007	12.221713500829852
2008	10.56618527478435
2009	10.09537203885202
2010	10.751167385057471
2011	10.03445107696491
2012	10.157070020416912
2013	10.624876408938105
2014	11.615100260050012
2015	10.638964111466104
2016	10.875049783579703
2017	11.107340444544956
2018	11.35028441764322
2019	11.474547749263778
2020	8.915525923824385
2021	11.12031645643473