Year	% of land area
1990	61.9774011299435
1991	61.75509819747108
1992	61.53279526499866
1993	61.31049233252624
1994	61.08818940005381
1995	60.865886467581376
1996	60.64358353510896
1997	60.42128060263654
1998	60.19897767016411
1999	59.976674737691695
2000	59.754371805219265
2001	59.60082055421039
2002	59.4472693032015
2003	59.293718052192624
2004	59.14016680118376
2005	58.98661555017487
2006	58.833064299166
2007	58.67951304815712
2008	58.52596179714823
2009	58.37241054613936
2010	58.218859295130486
2011	58.06529459241323
2012	57.911729889696
2013	57.75816518697875
2014	57.77558014031301
2015	57.621559633027516
2016	57.467620075553164
2017	57.313545601726936
2018	57.113372876786194
2019	56.95942302507414
2020	56.80560798058776
2021	56.65170261526018