Year % of revenue 1995 25.441378000764132 1996 26.13262167741764 1997 26.19824375533536 1998 25.863803991817306 1999 26.891558811873534 2000 26.743793959074765 2001 25.62386718093726 2002 24.232156481319965 2003 24.586118206949646 2004 25.14467148476293 2005 25.256190745944707 2006 25.353774214791024 2007 25.411022369007075 2008 24.44099984929896 2009 25.118105170169038 2010 25.379083280150766 2011 24.733808953350273 2012 24.968990832523623 2013 24.29718375639813 2014 24.08259532856199 2015 24.84615730666963 2016 26.53096040973223 2017 26.078653152284048 2018 25.9545567185749 2019 26.82077160816284 2020 26.28545467554671 2021 26.99865734592315 2022 25.47349108259654