Year	% of land area
1990	67.91416131038773
1991	67.83640887414472
1992	67.75865643790172
1993	67.68090400165872
1994	67.60315156541571
1995	67.52539912917271
1996	67.44764669292971
1997	67.3698942566867
1998	67.2921418204437
1999	67.2143893842007
2000	67.13663694795771
2001	66.85032044655779
2002	66.72383510693254
2003	66.625
2004	66.5193141912828
2005	66.40681466184823
2006	66.2943848059455
2007	66.17519603796947
2008	66.03567378080214
2009	65.89635277148156
2010	65.70987654320987
2011	65.61374627019241
2012	65.43006885212208
2013	65.24952271467576
2014	65.1442060966848
2015	65.03155626250705
2016	64.87911456677163
2017	64.78309916931597
2018	64.67391304347827
2019	64.51844262295083
2020	64.41598360655738
2021	64.31352459016394