Year % of revenue 1993 2.9881154499151115 1994 3.5743298131600367 1995 5.490446440786174 1996 4.76187020484847 1997 5.765730824679768 1998 6.286710861816987 1999 7.504347068270759 2000 8.384006761674453 2001 8.782783730980997 2002 5.898765185690454 2003 4.988167072626619 2004 4.620243836144357 2005 3.8916474413338316 2006 3.415937712178347 2007 3.1140255149270284 2008 2.73544801860734 2009 4.105640504755243 2010 5.398310710221757 2011 5.628961419613774 2012 5.352352722782022 2013 5.796226221956222 2014 5.3885969155140145 2015 4.68371217461819 2016 4.567914466334196 2017 4.0422419154868034 2018 3.602787649407837 2019 3.2941030151271233 2020 3.1527278314899014 2021 2.858086461073754 2022 2.8268295359482187