Year % of revenue 2008 0.9550515159297082 2009 0.7496717741679606 2010 0.7974171144199177 2011 0.7307636780777645 2012 0.6094043959868402 2013 0.6397647821101369 2014 0.5083591714671247 2015 0.6514667535216148 2016 0.35974333752673654 2017 0.3987488594059486 2018 0.34574644670497817 2019 0.4791839084616824 2020 0.5987930211260439