Year % of revenue 2010 34.806461086654494 2011 34.82052314824321 2012 39.115326972492845 2013 33.00806697530009 2014 34.333143298029434 2015 28.899085925892493 2016 17.01451095498391 2017 23.872198725992906 2018 24.39194825568186 2019 24.796621472933584 2020 18.688136358855907 2021 32.19289699622549 2022 30.247670268389154