Year % 2010 22.87470367165488 2011 22.939427592716964 2012 22.979969658652127 2013 23.01108870926252 2014 23.06216567231821 2015 23.08301998087244 2016 23.10107130767616 2017 23.130218879099505 2018 23.19817232659809 2019 23.247955074194202 2020 23.363986815064244 2021 21.9315850559153