Year % of revenue 1990 1.4142336999564808 1991 1.5071384233395406 1992 1.4891706633379322 1993 1.4928770605307586 1994 1.9175346631266028 1995 1.6956054940579766 1996 1.2501538756137929 2006 0.8606683481467784 2007 0.8706622836836683 2008 0.929479438134161 2009 1.2360500676816124 2010 1.644355188761322 2011 1.5283272194512385 2012 1.6156768814498776 2013 1.4063840443725242 2014 1.2565578909310615 2015 1.7027696395194964 2016 1.5311648909505282 2017 1.7565582960447241 2018 2.041919145692026 2019 2.2196743401133827 2020 2.4074747792072233 2021 1.7023267829070752 2022 2.180576428854168