Year	% of expense
1993	3.2228529573338265
1994	3.750532746128722
1995	5.076433382057622
1996	4.049324746848636
1997	5.153498129174446
1998	5.592326766025314
1999	6.92644174787032
2000	7.470945740975135
2001	7.621910101535557
2002	5.833175653116498
2003	4.864284547914295
2004	4.290626869934304
2005	3.9075392826610313
2006	3.407146808067427
2007	3.2643266861690314
2008	2.773285327447968
2009	3.39021003341972
2010	4.222231892541141
2011	4.612615460218032
2012	5.172231650098869
2013	4.735795633441106
2014	5.234742956080369
2015	4.660177913583617
2016	4.273063120379516
2017	3.8693078711764306
2018	3.334660632343336
2019	3.2014958734969365
2020	2.7569684374819747
2021	2.5206113629836575
2022	2.729406554817459