Year % of revenue 2007 42.65420171118447 2008 41.961221385234346 2009 43.48701510421068 2010 45.096479259422054 2011 45.59933356422191 2012 45.91382926965441 2013 39.438275858850986 2014 40.0834315838893 2015 41.13466896673275 2016 41.98581249366436 2017 41.33322376901984 2018 40.7160099023625 2019 40.412862857512756 2020 39.839493148833455 2021 39.839493148833455 2022 40.88013289061481