Year	% of land area
1990	91.38505619365198
1991	91.32985797208843
1992	91.27465975052489
1993	91.21946152896135
1994	91.1642633073978
1995	91.10906508583426
1996	91.05386686427072
1997	90.99866864270717
1998	90.94347042114363
1999	90.88827219958009
2000	90.83307397801654
2001	90.80317895516858
2002	90.77328393232061
2003	90.74338890947264
2004	90.71349388662468
2005	90.68359886377671
2006	90.65370384092874
2007	90.62380881808078
2008	90.59391379523281
2009	90.56401877238483
2010	90.53412374953686
2011	90.46069408422872
2012	90.3872644189206
2013	90.31383475361245
2014	90.24040508830431
2015	90.16697542299617
2016	90.09704828948995
2017	90.03712486105965
2018	89.96502408299371
2019	89.89282450290229
2020	89.82072372483636
2021	89.74855674941337