Year % of land area 1992 54.06828334396937 1993 53.174856413529035 1994 49.872367581365666 1995 54.4033184428845 1996 54.41927249521379 1997 54.51499680918953 1998 54.64262922782387 1999 55.77536694320357 2000 54.530950861518825 2001 46.202935545628584 2002 46.02744097000638 2003 40.539246968730055 2004 41.54913848117422 2005 45.26164645820038 2006 44.52297383535418 2007 43.01052967453734 2008 42.63422417231751 2009 42.90386916633426 2010 44.23294774631033 2011 44.7697609854166 2012 45.348948527299996 2013 46.1332269644994 2014 47.12529928172386 2015 47.979249800478854 2016 47.15526324191437 2017 46.859085902204626 2018 47.05412741497685 2019 47.50878313637815 2020 46.99457042478441 2021 46.92221689825906