Year % of revenue 2005 2.485105935369385 2006 2.9526494874866174 2007 3.943145346171481 2008 2.099094127157224 2009 3.2099850653621296 2010 4.208183067236572 2011 4.549268761307702 2012 4.155524192107869 2013 4.000480228124791 2014 3.4985602417243156 2015 3.2542899978616915 2016 2.8567329075564816 2017 4.554881692965229 2018 4.570999153680704 2019 4.964376467423386 2020 3.783680369052589 2021 4.962401673770189