Year	% of expense
2006	36.76415373288876
2007	28.227782078453618
2008	18.360575110037352
2009	23.453538333486357
2010	23.280114798407144
2011	21.968339589704655
2012	28.80936728303385
2013	28.830520248577812
2014	28.580890998801394
2015	33.696447978646724
2016	30.093259461454725
2017	33.95078467230332