Year % of land area 2006 38.28996282527881 2007 38.215613382899626 2008 38.141263940520446 2009 38.215613382899626 2010 38.066914498141266 2011 38.141263940520446 2012 38.141263940520446 2013 16.589591078066913 2014 17.124163568773234 2015 17.20446096654275 2016 19.01115241635688 2017 19.055762081784387 2018 19.092936802973977 2019 19.107806691449813 2020 19.178438661710036 2021 19.00074349442379