Year	% of expense
1999	0.5157956879079338
2000	0.8722587686047988
2001	3.665663117449748
2002	3.5000137460956675
2003	2.0144548488114364
2004	5.587780623786095
2005	2.692573896431536
2006	1.331004223386822
2007	2.250399564687713
2008	9.109975456409911
2009	7.367973281771841
2010	5.863643496793071
2011	2.9083880666181083
2012	3.586106818570287
2013	2.6625302261559667
2014	3.6735180468405413
2015	8.555260405219052
2016	12.300796535652776
2017	16.232162511047616
2018	27.578918036958267
2019	32.36511565421634