Year	% of expense
1990	12.410126469170946
1991	17.07031490725334
1992	12.221282432277974
1993	12.702323642015086
1994	13.952015203103969
1995	16.763526906981866
1996	12.77702100906376
1997	13.035103080474409
1998	14.7114600687675
1999	13.043478260869565
2000	13.240585704880974
2001	12.16148851958847
2002	12.075310478940468
2003	12.191153340827377
2004	12.407967715397973
2005	10.759027702021037
2006	10.781621236312748
2007	9.840761035835417
2008	9.81367382647758
2009	10.09537203885202
2010	10.866013629230936
2011	10.07258345321039
2012	9.904983202987395
2013	9.409821983945973
2014	8.553798658291647
2015	9.08056640333836
2016	10.875049783579703
2017	10.63128066218248
2018	11.645339584495003
2019	12.236846453443633
2020	9.686580729785145
2021	10.705945703319578
2022	12.494431415283472