Year	% of expense
1972	1.5819502074688834
1973	1.615110867779906
1974	1.8338220918866028
1975	1.9118841364374695
1976	2.2698378244286577
1977	2.608291989439166
1978	2.7104253408441585
1979	2.955891362058396
1980	3.2201418504412866
1981	3.8484285231497073
1982	4.526641485172383
1983	5.294336155154546
1984	5.229374768775431
1985	5.346987257936807
1986	5.346878527394306
1987	5.252911813643927
1988	5.22255098469665
1989	5.0532573693336795
1990	4.933274839732254
1991	5.168412596661771
1992	6.440352888850522
1993	6.365102281215883
1994	6.775890730235985
1995	6.120071227994309
1996	7.1609920080577
1997	7.17275494672755
1998	7.173637992158041
1999	6.748344736939084
2000	6.794725812508327
2001	6.432972709916521
2002	6.197470408330026
2003	5.7767460909586905
2004	5.722554701532152
2005	5.536750691448962
2006	5.5910710618123005
2007	5.8024705468863855
2008	5.784789924953851
2009	5.200032134734092
2010	4.649488791200048
2011	5.3422306223602245
2012	4.870596807905452
2013	3.595014753379321
2014	3.2296324439118957
2015	2.8002073265617677
2016	2.3427889386338383
2017	1.9722878997472097
2018	1.8055666405946549
2019	1.5139792883658534
2020	0.953284893913705
2021	0.8651117321686564
2022	1.3419764442528994