Year	% of expense
1991	64.99276244365592
1992	58.901345805300195
1993	62.892231686144676
1994	62.22449099695537
1995	49.15908521826225
1996	50.28359511343804
1997	51.56120598965911
1998	51.744108934966185
1999	51.60503421626406
2000	51.295851976741666
2001	50.8898498898083
2002	49.894980994494844
2003	49.17688451628016
2004	48.284740941814555
2005	47.51047449990756
2006	47.95140325253483
2007	48.80681718742061
2008	49.158529625001925
2009	49.97840794587592
2010	50.98549088957481
2011	50.214643771331055
2012	51.42957963178455
2013	52.76762453246644
2014	52.54257666930778
2015	53.2924325774986
2016	53.85704142019694
2017	54.57643993569329
2018	54.31545745111538
2019	55.30891653704903
2020	55.046474343073726
2021	56.40512195519143
2022	57.7920352152262