Year	% of expense
2001	14.871686713718132
2002	14.301817870494563
2003	15.713477323736798
2004	18.063189717136694
2005	19.015653088963916
2006	15.843624406284254
2007	17.0394664331269
2008	13.741690408357075
2009	18.693743194237705
2010	18.18775077249458
2012	22.016120771209984
2013	21.416850176557126
2014	21.84895549624142
2015	21.789652218128122
2016	23.17592573252544
2017	21.909812435491332
2018	22.458518806319855
2019	22.071285127259717