Year	% of expense
2000	7.5473439353348475
2001	10.169064595693952
2002	10.792348042250014
2003	10.999663513985602
2004	12.621435671658828
2005	14.57836259763296
2006	16.32299944163482
2007	16.806382452841905
2008	12.495233080795572
2009	13.575617619558708
2010	12.835502497353382
2011	13.443156786342241
2012	14.91532793718153
2013	15.898344917242088
2014	16.59346676807277
2015	16.751509144968015
2016	16.284701390782654
2017	16.068948099507512