Year	% of land area
1992	82.03244804978331
1993	82.13764492351002
1994	82.10208541689818
1995	80.44838315368375
1996	79.81390524873134
1997	79.89472904396784
1998	79.76064007111901
1999	79.6663703374449
2000	79.78416120309663
2001	79.44793865985109
2002	79.07134126014002
2003	78.89817387117087
2004	78.77560469681816
2005	78.63318146460718
2006	78.48149794421603
2007	78.31818350187058
2008	78.10178908767641
2009	78.07656406267363
2010	80.43923398896173
2011	80.37504167129681
2012	80.3837833833389
2013	80.37711597584916
2014	80.30499685150203
2015	80.10508575026854
2016	80.0985665073897
2017	80.08804682001703
2018	80.02226173278513
2019	79.2585472459903
2020	79.26925213912656
2021	79.19246582953662