Year	% of expense
1990	23.602583573744273
1991	35.55670595731124
1992	12.496328807772265
1993	19.88555634257056
1994	17.357423419711157
1995	34.85796822339913
1996	11.779247265311167
1997	23.31650759362532
1998	59.51585571954763
1999	42.15646534252128
2000	27.13746607399213
2001	18.674090042763087
2002	17.353473341854155
2003	20.470980902231737
2004	22.081477009515254
2005	19.735655111754415
2006	22.418498044910525
2007	27.32245186263096
2008	33.07952338708049
2009	32.073238011709
2010	42.60517255086627
2012	32.773156374239235
2013	35.51315396590398
2014	38.24751459916265
2015	40.64983872795787
2016	42.2929099680993
2017	48.45280496532282
2018	35.44775879813757
2019	52.78442063542948
2020	58.12564159196854
2021	53.656196033174034
2022	37.385820378897236