Year Number 2006 0.7974747915222619 2007 1.0888427142452697 2008 1.5512190978568854 2009 1.1714646163692302 2010 1.3155507669524473 2011 1.3130029548484845 2012 1.295743211824658 2013 1.3064552759138661 2014 1.7346455522345445 2015 1.5954404353727407 2016 1.8368206971564547 2017 1.773504300031756 2018 2.0205243912027355 2019 1.789107537421046 2020 1.9488452697043872 2021 2.0417245925458207 2022 1.7483495927159058 2023 1.521859719448221