Year	% of revenue
1990	10.407299062553774
1991	9.282934821565716
1992	8.927137997127677
1993	9.200231976912773
2001	31.24842772877748
2002	17.211137033428553
2003	25.485751919713895
2004	30.346689528171133
2005	29.303835689596113
2006	26.74734192342229
2007	29.786658420109564
2008	25.57377078501591
2009	32.14649632428031
2010	30.416558375605156
2011	30.64691904131368
2012	26.39719647778921
2013	27.99174148544093
2014	23.600493060770212
2015	26.91050687407849
2016	24.662637062921984
2017	23.35413539130627
2018	20.68266726570957
2019	19.867153640727206
2020	19.388444710498124
2021	19.349643895936033
2022	21.834196779446305