Year	% of expense
1990	52.17757042799699
1991	54.946240183356366
1992	56.969974488127164
1993	57.4240552170764
1994	56.859096370809105
1995	55.54112865148934
1996	55.21753387011986
1997	55.65864114666782
1998	55.3181061196956
1999	56.38468298807282
2000	55.125735584470625
2001	57.45304780671853
2002	58.378065785853195
2003	60.57343077562057
2004	61.29127371273712
2005	64.1563495289702
2006	63.422176178815846
2007	64.5143209461353
2008	65.0174156946142
2009	66.25216868852569
2010	67.3902377657567
2011	66.13468066629825
2012	67.23329407243791
2013	67.90431911679184
2014	68.95178543049596
2015	70.47899518501612
2016	71.43381108227062
2017	71.09744384362712
2018	70.88997518850869
2019	71.4748846347583
2020	80.0375766230532
2021	75.94308370229369
2022	70.34577918022296