Year % of revenue 2009 4.461086693355827 2010 4.461086693355827 2011 4.392882668574524 2012 4.85322794989012 2013 6.401587267878041 2014 8.435022926953167 2015 9.418920691583697 2016 10.429920855900543 2017 9.92983630531227 2018 10.345749010458738 2020 10.415168098144706 2021 11.464774830671875 2022 11.407308731214865