Year	% of expense
1991	2.1569951725324743
1992	1.7561247107300733
1993	2.099373369263014
1994	2.4230068769056112
1995	5.984982443436639
1996	5.166180948349048
1997	5.125403358461145
1998	5.7424323480881805
1999	5.256685233157499
2000	5.425228448976199
2001	6.506361408289529
2002	5.764762211866381
2003	5.809014508526818
2004	6.254052098249307
2005	6.771208927518147
2006	6.581554811182085
2007	6.3778241676015615
2008	6.30534770464219
2009	6.192065893474258
2010	7.131555082218055
2011	6.949731929032324
2012	7.185176656220246
2013	6.419971428011719
2014	6.481795748805987
2015	6.592856235787246
2016	6.420435796711417
2017	6.6206819744369785
2018	6.411586373982625
2019	6.312148098829047
2020	6.698941447308323
2021	7.20050348018443
2022	7.925000826175231