Year	% of expense
1972	9.890415187528939
1973	9.712259648165826
1974	10.366240914543786
1975	10.409727517155584
1976	9.375
1977	9.212007237395108
1978	8.914480961628279
1979	8.886253297568112
1980	11.376761376761376
1981	12.183282524165847
1982	11.770094056493473
1983	11.991318137834641
1984	11.482055047230054
1985	11.111173926562456
1986	10.750315738218779
1987	11.078585497190147
1988	10.740414352698613
1989	11.094470621215088
1990	11.924399106624005
1991	12.139264356516753
1992	12.335399035455373
1993	12.523710067451956
1994	12.422457702220143
1995	7.193951380169652
1996	7.3108975794574
1997	7.383493921588105
1998	7.2339549371173835
1999	7.35930735930736
2000	7.430335422424106
2001	8.358327590527503
2002	9.297997367511412
2003	8.7310761182594
2004	8.74550288386495
2005	8.764426207465444
2006	8.562751533540373
2007	8.476595857357525
2008	8.518322817269139
2009	8.724080257880818
2010	8.56019214975832
2011	8.236219979986657
2012	8.160407409137486
2013	8.275952788334873
2014	8.386984451834797
2015	8.484738356879024
2016	8.574395849686821
2017	8.69416104203947
2018	8.75090834472294
2019	8.912919035596307
2020	8.494999497213032
2021	8.974138443500335
2022	9.401538269931988