Year % of revenue 2010 24.157970360165017 2011 26.005978873751644 2012 23.16762871111406 2013 24.00012052842793 2014 26.926253696335152 2015 39.91163560523836 2016 32.616602816608356 2017 31.28442508165017 2018 29.863016530858495 2019 23.742775956623156 2020 21.661087038594236 2021 23.93576812222905 2022 25.853722937051867