Year % of revenue 2010 20.709355004383358 2011 23.429558354528968 2012 29.54656099570413 2013 31.968434013027835 2014 35.496581707542276 2015 33.11537735382304 2016 35.770900942272796 2017 44.29575522041424 2018 39.795670005227606 2019 50.25630501461625 2020 37.81598901063348 2021 34.71184546525071 2022 37.29684355803349