Year	% of expense
1990	3.6678403755868545
1991	4.998837479655894
1992	3.9733875438920716
1993	5.047215890589384
1994	8.108108108108109
1995	8.711991800478305
1996	8.478124345823739
1997	7.368866328257191
1998	6.287079127821866
1999	6.386282756389518
2000	5.671944133482595
2001	5.909505934868621
2002	6.471034417369868
2003	5.763737903397707
2004	4.9711272909866935
2005	3.335989490233239
2006	3.545062234744463
2007	3.5715918964649926
2008	3.7517418801586455
2009	7.0497096373033346
2010	8.018414589290588
2011	7.997140993667341
2014	6.978568561905112
2015	8.005928565558206
2016	7.207874169009671
2017	7.272869573346413
2018	7.880810169374436
2019	6.858037972223999
2020	7.946090069892525
2021	8.842347246007803