Year	% of revenue
2012	29.022904236646497
2013	24.17313531405398
2014	29.15504240975002
2015	24.76993969598429
2016	23.928456278331634
2017	25.013239010799783
2018	27.790914015532408
2019	29.091708075314976
2020	37.86588670083981
2021	36.4508841012734