Year	% of expense
1990	20.91652405400266
1991	20.467513344376957
1992	21.611526147278546
1993	18.90538033395176
1994	18.263205013428827
1995	19.173942243116183
1996	22.26438002731826
1997	21.69511340052636
1998	22.303284882489507
1999	21.471462769308303
2000	20.2268887279749
2001	21.314878892733564
2002	21.838083884252736
2003	23.343343343343342
2004	19.492077231206988
2005	19.700295211275673
2006	20.11979471473072
2007	20.922186176730133
2008	21.160103019812876
2009	22.445762837037066
2010	20.744009410607553
2011	22.900211244103136
2012	21.822358674720128
2013	23.148020936161963
2014	20.527258987809834
2015	19.43593707673001
2016	20.34482729856601
2017	23.434126232404985
2018	20.14057564758446
2019	24.104212881102193
2020	20.975259881439314
2021	20.669026898511206
2022	20.58373225095502