Year % of revenue 1984 24.565426042444276 1985 24.495372410753635 1986 24.54453161052146 1987 24.308596887360014 1988 21.31208571688005 1994 24.588395594413534 1995 30.592156542524368 1996 27.65631797715705 1997 33.321483221787716 1998 34.26744722759201 1999 40.599335178675915 2000 40.24448461797322 2001 41.58723580605056 2002 39.72638723235077 2003 39.273550842217816 2004 39.94395789943958 2005 39.22127641009358 2006 38.26531884302878 2007 37.045326260836134 2008 35.95028115649346 2009 37.96058427579445 2010 36.6680625863861 2011 36.94744703431469 2012 39.40222096743835 2013 41.0955087379774 2014 40.63300371334256 2015 40.85764497206979 2016 41.36134379641112 2017 40.62451918983393 2018 40.275857735327385 2019 40.58570730336083 2020 40.82112574990603 2021 38.054512760654916 2022 39.67766633635199