Year % of revenue 2002 12.552245097124853 2003 11.090004078896962 2004 10.890187022775109 2005 8.914387544403555 2006 7.94322329639236 2007 7.4125134803827315 2008 7.633663770417525 2009 6.676163534374185 2010 6.1872098702879565 2011 5.524876492814335 2012 5.637406336040727 2013 6.539282322328883 2014 7.1441449558441406 2015 6.286253999764064 2016 7.166752434908604 2017 8.59447390010504 2018 10.619083040878966 2019 10.437210976333127 2020 10.856416101443829 2021 8.07965540683504