Year % of revenue 1995 5.124162396531337 1996 12.172442941673712 1997 12.783536127384707 1998 18.10600706713781 1999 18.59832441957523 2000 19.35483870967742 2001 10.88351422049432 2002 13.105586177939376 2003 13.305432722678459 2004 6.353455583812965 2005 4.432388544434603 2006 2.8153626355155894 2007 2.0106519136286694 2008 2.1315371008951383 2009 3.35493709492947 2010 3.6458427946011738 2011 4.348427982526302 2012 3.4543203349981217 2013 3.0424904024444386 2014 2.9318105636163385 2015 3.3685383060357275 2016 3.798616948116451 2017 4.012527572446076 2018 4.349802587825267 2019 4.526439027300318 2020 6.055389280665872 2021 5.185319485094149 2022 3.8975768505698976