Year % 2001 16.42884314365645 2002 17.40370572542913 2003 16.680747524585176 2004 17.3791192732543 2005 18.456683758552533 2006 18.110987194923936 2007 19.35570520853896 2008 17.192778101339545 2009 18.444265678178922 2010 18.41313767469805 2011 16.8960727250315 2012 18.18874492743073 2013 20.596504438583043 2014 18.591527707591343 2015 18.54060054885867 2016 18.072060337726093 2017 18.831126253109367 2018 18.25527099262194 2019 18.8312792609576 2020 18.566680997967474 2021 19.500355529644224 2022 17.302971026241906 2023 15.57235752411192