Year % 2006 16.3220249655905 2007 19.5181675698801 2008 19.7985047697707 2009 20.4927940228581 2010 20.0600853846952 2011 19.6894645478461 2012 20.6881832387283 2013 20.5843753160471 2014 21.950993327245 2015 21.0716527701701 2016 22.1878592445165 2017 23.4831682957972 2018 22.999768451289 2019 22.9594261289926 2020 23.8832975589217 2021 11.6425477501666 2022 9.94098978572859