Year % 2011 8.0723723842756 2012 8.01952585078312 2013 7.95696644289845 2014 7.38359019833843 2015 8.17832099493576 2016 8.92436205660615 2017 8.88864619461054 2018 9.34211576597437 2019 10.1990810675071 2020 10.3263743113916 2021 8.61977114859705