Year	% of expense
1990	12.246482290150412
1991	13.675966715614294
1992	12.81164695177434
1993	10.686775318251843
1994	8.369743309666848
2000	14.435784479837343
2001	17.06840390879479
2002	9.550419844952156
2003	10.21683528371332
2004	9.566684252908672
2005	11.62776210079422
2006	12.12586783335964
2007	11.950727577680134
2008	23.925617357913946
2009	22.58773896191094
2010	24.71611272494058
2011	21.13729577085995
2012	21.346484646634703
2013	14.458239680331086
2014	12.53215847697453
2015	7.409320747037368
2016	25.626974864072423
2017	6.239300562484715
2020	2.944862155388471