Year	% of expense
1972	2.7090427544457083
1973	2.851413172902171
1974	4.538520213577408
1975	5.7362698120162054
1976	5.523637557452384
1977	6.03841267468798
1978	5.665016555748646
1979	5.623026475589008
1980	6.0415904550187225
1981	6.050531914893606
1982	5.724894832083842
1983	5.7387589634053455
1984	5.528103767757861
1985	5.747126436781598
1986	6.441555600123975
1987	6.273981126205539
1988	5.467766974426018
1989	5.363382250174696
1990	61.87577934801981
1991	62.30310654123827
1992	62.39004423653829
1993	62.892231686144676
1994	62.90455323976241
1995	69.684055129092
1996	70.18975480726378
1997	71.60708786419231
1998	71.20292128124457
1999	72.03984153937935
2000	71.9498454045614
2001	71.61015593042931
2002	72.94826959814661
2003	73.260746695092
2004	67.51310545896102
2005	70.02196878250322
2006	70.16128185990355
2007	70.5181595705386
2008	70.78106629530674
2009	68.9530991337378
2010	70.71775675654231
2011	70.96708069402642
2012	71.12681631037536
2013	71.77870872543468
2014	70.37155650416301
2015	73.33300729922975
2016	73.4223310021224
2017	73.46842541455023
2018	74.00399192734083
2019	74.28793001643879
2020	76.11962978785415
2021	75.96076804282717
2022	73.81577438408482