Year	% of expense
1992	7.790958640589933
1993	8.105348508964234
1994	10.8775994263335
1995	12.182901329545903
1996	12.832897774071853
1997	10.33434650455927
1998	11.659877507043632
1999	12.570771451640528
2000	12.679114198871039
2001	11.557471320542017
2002	14.211972303151788
2003	29.53913967155522
2006	24.245838667288506
2007	23.98915662209756
2008	32.649005918555325
2009	33.23587498944491
2010	29.206010646150887
2011	24.905850712841158
2012	26.495928519015717
2013	18.319224853567352
2014	18.01006953124049
2015	18.660597471165413
2016	16.144029679244348
2017	18.096957935269096
2018	16.992326446479023
2019	15.49365488469919
2020	14.086423381547863
2021	9.887304539424946