Year	% of expense
1990	12.620274745732818
1991	12.950458994006524
1992	14.963995885244028
1993	19.592539624468316
1994	20.601627179136145
1995	29.144996696277808
1996	30.234536581389897
1997	26.608522291878785
1998	30.707710718502412
1999	28.896163713808814
2000	35.01204608386797
2001	39.30787126793331
2002	29.27951420394754
2003	30.958329581342177
2004	37.12345707079808
2005	37.13990351481737
2006	35.305350990222934
2007	37.78531128056971
2008	35.67991237173165
2009	36.01891699857008
2010	36.627305352123365
2011	34.00584094248524
2012	33.62632266194245
2013	33.7068844259777
2014	32.34877497087901
2015	34.376865503299086
2016	31.80672372049937
2017	31.879758273133298
2018	31.998843623260953
2019	28.933973705567258
2020	30.81321945067786
2021	37.00333275132952
2022	33.07654941192797