Year % 2001 16.31164021219908 2002 14.818094498795128 2003 15.174277202772224 2004 17.92724293228851 2005 19.431614574498933 2006 19.149638649623206 2007 18.237494038804247 2008 16.742654145601378 2009 21.271622236160603 2010 21.76735699586691 2011 21.261957835669747 2012 20.31968117989341 2013 20.504133385185558 2014 19.5305023155101 2015 20.969494534385813 2016 20.503361400007172 2017 19.49430466845547 2018 19.49824801628374 2019 19.51181610489767 2020 20.781186032330695 2021 22.641199531269457 2022 21.221405725588347 2023 22.225403719861184