Year % of revenue 1991 39.4076956333766 1992 33.968955112452235 1993 37.61283239814576 1994 39.41376727072719 1995 31.174370872746742 1996 34.63942662923009 1997 35.040607030647934 1998 32.436260623229465 1999 32.022489622195366 2000 34.26664185700331 2001 35.81021087680355 2002 35.27936909456142 2003 33.74086095537851 2004 35.63309246423832 2005 37.10565097398247 2006 37.795341455044614 2007 37.20849420849421 2008 33.37609349607551 2009 34.41383827762743 2010 35.01031260648887 2011 36.17148687754044 2012 36.790220334810435 2013 36.12661764705882 2014 37.09300716716938 2015 37.092553895674065 2016 38.818217020372984 2017 37.84611125849203 2018 37.20387092666674 2019 37.579381643449985 2020 35.18491952758072 2021 35.398876935909676 2022 35.50906364999318