Year	% of expense
1990	8.025922959295128
1991	7.1804735690124035
1992	6.755382268181048
1993	8.089785943793276
1994	9.198862686067905
1995	11.118941893194858
1996	11.804325446277856
1997	9.657202544867534
1998	9.28546081888123
1999	10.37077984281599
2000	13.981524761997639
2001	15.86429247515381
2002	18.145840135137053
2003	19.18152596613943
2004	32.68958389870519
2005	28.017779462497472
2006	27.42144909978993
2007	18.159635853472505
2008	16.146636143764763
2009	14.317979011059476
2010	14.985851463561719
2011	14.036699890138978
2012	8.124859408498223
2013	10.903976526010533
2014	10.884282870814921
2015	9.399174922677295
2016	9.096298901204605
2017	10.335984849393984