Year % of revenue 1994 8.11035996556368 1995 8.852382351140962 1996 9.148829796742906 1997 10.109271233006702 1998 9.706441925187503 1999 8.07984254726699 2000 7.925765041522509 2001 6.810061304620978 2002 6.47816726225619 2003 5.994148128687647 2004 4.916485443053649 2005 4.190168996582765 2006 3.9833053088398103 2007 3.2891500217871052 2008 3.1947906598158418 2009 3.9974315232600484 2010 4.286382549178915 2011 4.455168265214049 2012 4.926251847802637 2013 4.929022136738183 2014 4.761305204777627 2015 4.480334929703263 2016 4.567914466334196 2017 4.138206670579482 2018 3.7849660544161763 2019 3.6999237729599135 2020 3.6506184542926055 2021 3.2716476701148016 2022 3.2875394196408205