Year	% of expense
1995	5.076433382057622
1996	4.681228630769044
1997	5.153498129174446
1998	5.592326766025314
1999	6.987961668589529
2000	7.547579426653008
2001	8.896841171998148
2002	7.888244976838589
2003	6.217018163293641
2004	5.749513785901588
2005	4.425114338269649
2006	3.817628460975674
2007	3.9254733610832737
2008	3.7263151248495734
2009	3.39021003341972
2010	3.188101074950082
2011	3.8100978537202663
2012	4.419723152820443
2013	4.64154572205547
2014	4.740414388998433
2015	4.248432510485383
2016	4.108081036164025
2017	3.8294160987957753
2018	3.5702619388051167
2019	3.2014958734969365
2020	2.7569684374819747
2021	2.5206113629836575
2022	2.5676855280144895