Year	% of land area
1990	10.651374363832913
1991	10.565124561211723
1992	10.478874758590534
1993	10.39262495596934
1994	10.306375153348151
1995	10.220125350726962
1996	10.133875548105772
1997	10.04762574548458
1998	9.96137594286339
1999	9.875126140242198
2000	9.788876337621009
2001	9.702625563288755
2002	9.616374788956504
2003	9.530124014624251
2004	9.443873240292
2005	9.357622465959746
2006	9.271371691627495
2007	9.185120917295242
2008	9.09887014296299
2009	9.012619368630737
2010	8.926368594298486
2011	8.840119520460592
2012	8.753870446622697
2013	8.667621372784803
2014	8.581372298946908
2015	8.495123225109014
2016	8.408871721993465
2017	8.322620218877917
2018	8.236368715762369
2019	8.15011721264682
2020	8.063865709531271
2021	7.977614206415722