Year	% of expense
1990	48.11416167147685
1991	56.686847937726355
1992	44.59366699495628
1993	47.35842366528214
1994	41.175762439807386
1995	39.68064153066967
1996	41.10805173133083
1997	31.79932646306387
1998	25.686049077332218
1999	21.75411537326364
2001	23.27935426153212
2002	16.08061490044181
2003	16.959585740985236
2004	13.751239552344524
2005	12.34318420012175
2006	21.38256660513828
2007	27.468727921289915
2008	15.853266815117117
2009	14.971283047624611
2010	14.464349004806525
2011	12.801116099717513
2012	10.263546778565388
2013	9.339089554366529
2014	9.869325877916044
2015	10.805810063333464
2016	10.510231375343475
2017	11.110281530741945
2018	11.764620573335565
2019	12.088592306535686
2020	13.670323609788685
2021	12.915834763498282
2022	14.529181557237466