Year	% of expense
1990	18.909756097560976
1991	18.343389566145383
1992	18.547848487739717
1993	23.714345536246356
1994	22.629571460623737
1995	18.434812843521403
1997	13.477853470762529
1998	15.727431922620378
1999	13.03373304942284
2002	12.880379909764821
2003	14.379399144719393
2004	10.547293588730133
2005	15.162799969124594
2006	9.454707086294778
2007	8.664261927633191
2008	9.150396362562137
2009	8.881822136439855
2010	9.011649873422847
2011	8.369656240779522
2012	8.33939078069579
2013	8.611203107725636
2014	9.289859860870536
2015	10.110336705537106
2016	10.688042122522722
2017	10.275534935081401
2018	10.828817921783559
2019	10.754975922413736
2020	10.559806996590655
2021	13.78225161747415
2022	10.084597927480655