Year % of revenue 1990 7.210031347962382 1991 9.657534246575343 1992 13.324372371330703 1993 15.528950295650137 1994 20.63841259570797 1995 12.989869574646054 1996 12.259694461623486 1997 10.420962295063696 1998 9.822520083828152 1999 10.32727947008952 2001 9.769259567007863 2002 10.091042673190236 2003 8.749483755506608 2004 6.864719704598858 2005 6.524998828545991 2006 17.79064228923167 2007 14.3839795508654 2008 4.289628398783766 2009 2.898071163794006 2010 2.612860390531956 2011 2.5875650522382907 2012 2.8893485197159805 2013 2.829069636835558 2014 3.0107267564388 2015 3.6854242215092112 2016 4.126097380109371 2017 4.59660538983931 2018 4.961557894322891 2019 5.165304221501358 2020 4.489922522318574 2021 7.635870983971834 2022 12.792181101012792