Year	% of expense
1990	7.518882220286605
1991	7.023043131439101
1992	6.8685811473801275
1993	7.436304375612458
1994	7.552396244271238
1995	7.00223759571367
1996	7.070696555995649
1997	6.901441995409864
1998	7.251196323544912
1999	7.167859384808538
2000	7.381367440695759
2001	7.847623672684143
2002	8.26357247123676
2003	7.988176138422248
2004	8.107967479674796
2005	7.489117179267585
2006	7.990362277892886
2007	7.513405451861817
2008	7.520542041416147
2009	7.110935590794634
2010	7.349037614794314
2011	7.781479434751717
2012	7.588079267435431
2013	6.903448339523134
2014	7.125218518111026
2015	7.12558714826322
2016	7.167926870556371
2017	7.577196771506046
2018	7.440387395864412
2019	7.116477713559982
2020	4.945487101162133
2021	6.10195575280182
2022	7.783250474190033