Year % of revenue 2004 25.728079408925552 2005 18.919286375743717 2006 18.179968284546895 2007 19.036774985450016 2008 17.063792361902753 2009 16.697678016816567 2010 10.012706381471814 2011 10.31328664357102 2012 10.415359093307739 2013 12.069606714085232 2014 11.887157617980723 2015 17.427290267469157 2016 12.57691255663815 2017 14.121635997498775 2018 14.227169177125912 2019 15.97132354730341 2020 15.792167161405493 2021 20.46567830129306 2022 18.22363643116062