Year	% of expense
1992	54.63917525773196
1993	39.50307091010609
1994	34.848143559710174
1995	55.10054938913774
1996	63.590827385473936
1997	65.64219788321417
1998	67.50677056817794
1999	63.18632668942799
2000	67.65506454902096
2001	67.84523969470942
2002	68.6018624883924
2003	62.91458410844902
2004	61.16425598894737
2005	64.7098448054477
2006	64.52262827745619
2007	68.43923684317812
2008	69.12139504147125
2009	69.65203243201555
2010	69.26549788729524
2011	70.17432796575595
2012	69.31464648134069
2013	71.38764439237788
2014	70.61844246002451
2015	69.95168126072903
2016	70.3483376144818
2017	64.13358820187675
2018	61.69625347681487
2019	64.60094387735931
2020	61.09167579734651
2021	63.02244585869781
2022	62.47015805575518