Year	% of expense
1972	20.220168241769667
1973	21.463000981879894
1974	21.999775893624168
1975	20.01697097378276
1976	19.72911512607147
1977	19.61199687813583
1978	19.901149036836834
1979	19.74414128835059
1980	20.144203726115222
1981	17.28717349401252
1982	20.783822667448213
1983	18.388552934162377
1984	18.904084100846593
1985	19.823565898596335
1986	20.33933352197285
1987	20.707365120205857
1988	19.780600353809998
1989	20.387247838616705
1990	20.9761396702231
1991	19.322399473382
1992	21.81711727645869
1993	19.679982034079117
1994	19.096177334268862
1995	23.408137808676756
1996	22.992280787945845
1997	22.883042008733465
1998	22.747226294247366
1999	22.376350933165746
2000	22.227956621186593
2001	22.268366167229285
2002	21.737061053057698
2003	21.430259080339695
2004	21.022278948197297
2005	21.137805357562552
2006	21.03241533459407
2007	21.05808998503759
2008	20.326131925456078
2009	19.9127987603916
2010	20.102010857824006
2011	20.18826902720486
2012	19.822823476478476
2013	19.745039250959305
2014	19.950125253615987
2015	20.18490577725914
2016	20.009702700059037
2017	20.2032984841334
2018	20.49459803204344
2019	20.74156814715349
2020	20.285066871183467
2021	20.862159729698057
2022	20.390824298631507