Year % of revenue 1984 7.552433534074489 1986 2.049798223531419 1987 8.225003104347465 1988 9.396641499609476 1989 14.39988892712763 1991 7.441774954200264 1992 6.6525820235927196 1993 4.913818711432884 1994 4.254878502037568 1995 4.725232736739363 1996 1.558317338765411 1997 2.4680712752152396 1998 6.290531677862965 1999 4.503495733384297 2000 6.62609101727739 2001 5.162418032134413 2002 6.6303370964507184 2003 6.1411173611490355 2004 3.695734417856805 2005 2.5336857713880474 2006 4.724204307437313 2007 4.202833376158079 2008 1.3080036274074982 2009 1.339901784324381 2010 1.03335196463399 2011 1.4434097493821656 2012 1.2498026803557918 2013 1.429757727074143 2014 1.198782590294436 2015 1.7433509324130212 2016 1.7572479284045242 2017 2.1585699066067674 2018 2.783891769677337 2019 3.0505670349817837 2020 2.9198700812206515 2021 2.408649721939865 2022 3.347502783548304