Year	% of land area
1990	68.43115743280308
1991	68.4108612177729
1992	68.39056500274273
1993	68.37026878771256
1994	68.34997257268239
1995	68.32967635765222
1996	68.32812071330589
1997	68.30781893004115
1998	68.28751714677641
1999	68.26721536351165
2000	68.24691358024691
2001	68.27160493827161
2002	68.2962962962963
2003	68.32098765432099
2004	68.34567901234568
2005	68.37037037037037
2006	68.39506172839506
2007	68.41975308641976
2008	68.44444444444444
2009	68.46913580246914
2010	68.49382716049382
2011	68.48175582990397
2012	68.46968449931413
2013	68.45761316872428
2014	68.44554183813443
2015	68.43347050754458
2016	68.42249657064473
2017	68.40877914951989
2018	68.40877914951989
2019	68.40877914951989
2020	68.40877914951989
2021	68.40877914951989