Year % of revenue 2010 6.616770948755521 2011 7.064829098849825 2012 3.070309627611557 2013 4.3429447556811835 2014 3.8851156605103645 2015 3.8329661977917597 2016 2.818615695881171 2017 3.0134041603156074 2018 5.021804819646126 2019 4.079026817861258 2020 5.017004433056874 2021 3.7102644194833063 2022 4.964239765574159