Year	% of expense
1972	1.1071744906997343
1973	1.757890531362365
1974	1.9708914493632503
1975	1.8100890207715135
1976	2.3136872868972236
1978	2.414800389483934
1979	7.0605540573670025
1980	6.944593291179937
1981	7.777545473552164
1982	7.637284032133818
1983	9.273039496279337
1984	6.834874276332843
1985	3.1474980662819063
1986	1.1380652890086853
1987	1.2055804158989207
1988	0.7762174697242978
1989	9.536118291225437
1990	6.759323827157525
1991	10.686267375009097
1992	6.367994027856905
1993	11.723033591398773
1994	8.824387496862004
1995	9.147407851182155
1996	5.543809824339959
1997	3.8782022252722372
1998	4.003324304358532
1999	4.72176498699092
2000	5.688599891240209
2001	5.9050218556788625
2002	7.777025686120828
2003	11.693899579262453
2004	12.427885724860435
2005	8.527491118377597
2006	9.48012350134452
2007	8.496442395356551
2008	9.873560873635382
2009	12.213989151805107
2010	12.711757835816382
2011	14.480836883143775
2012	15.137791999745723
2013	14.633287926213365
2014	15.305359910722864
2015	16.44093797532677
2016	16.98201823376967
2017	17.912456394639207
2018	16.48675789092421
2019	17.316347927323672
2020	15.147448961787626
2021	17.498733528783948
2022	16.212537930904123