Year	% of revenue
1991	15.423111919927207
1992	16.178566163824872
2009	29.00016457720229
2010	36.234905480534316
2011	30.98511196802685
2012	20.929453655817927
2013	31.512057647336277
2014	22.444533718764227
2015	23.5118750481792
2016	20.08792319212585
2017	22.694621826564514
2018	21.189101136590967
2019	22.160817005287996
2020	20.57534882784241
2021	18.223379276716805
2022	20.036739922344264