Year	% of revenue
1995	8.319688270773312
1996	10.028547846941894
1997	6.484383952178943
1998	6.523514185837041
2002	13.881324172346773
2003	13.480667234117922
2004	14.834583051640887
2011	14.737241025690514
2012	14.205256103112598
2013	14.331150045143634
2014	13.813682071934341
2015	14.919001918127659
2016	11.481719355389345
2017	15.530392267832346
2018	16.681161944886387
2019	18.37448413433442
2020	15.36713044432448
2021	13.558278403735022