Year	% of expense
1999	48.3980720448548
2000	40.813965070507074
2001	47.913411822967944
2002	54.207311077240774
2003	55.02218451842378
2004	46.05859257376657
2005	52.88913897241159
2006	54.99904743760716
2007	52.79706109215463
2008	59.08098742095906
2009	62.049179012246604
2010	60.5229531471841
2011	59.83144066226864
2012	59.44156521950214
2013	61.18993262431093
2014	66.26792136966235
2015	68.90078233913681
2016	71.20995149093861
2017	70.63531651308278
2018	68.80756375748108
2019	69.04162464986373
2020	74.19461468341778