Year	% of revenue
1991	20.42411717135412
1992	23.67205542725173
1993	16.632012629471333
1994	23.314069473294534
1995	26.571002374099205
1996	18.813443557314113
1997	17.42011663212685
1998	28.52548420557554
1999	19.739502219606035
2010	3.4812145842805107
2011	6.387546712908689
2012	5.751468396147529
2013	5.03959817943316
2014	5.985462286826978
2015	18.07651289443658
2016	17.967469845084178
2017	13.393664288961329
2019	7.2699269254744525
2020	7.8990172661892455
2021	9.993548727798157