Year % of revenue 1997 0.5422194146136029 1998 0.6350197793046013 1999 0.4550625711035267 2011 7.2755863554619165 2012 7.259738343449845 2013 8.112907758689099 2014 8.5329215507042 2015 6.652961935514451 2016 6.946118110848063 2017 6.803183740765559 2018 6.810373345427132 2019 5.3519861423715405 2020 13.890051767422326 2021 17.408209288859943 2022 6.97473944930372