Year	% of land area
1990	62.23674911660777
1991	62.06643109540636
1992	61.89611307420495
1993	61.72579505300353
1994	61.55547703180212
1995	61.38515901060071
1996	61.2148409893993
1997	61.04452296819788
1998	60.87420494699647
1999	60.70388692579506
2000	60.533568904593636
2001	60.363250883392226
2002	60.192932862190816
2003	60.022614840989405
2004	59.85229681978799
2005	59.68197879858658
2006	59.51166077738515
2007	59.34134275618375
2008	59.17102473498234
2009	59.000706713780914
2010	58.830388692579504
2011	58.659363957597165
2012	58.48833922261484
2013	58.31731448763251
2014	58.14628975265017
2015	57.975265017667844
2016	57.80565371024735
2017	58.672661870503596
2018	58.5
2019	58.3273381294964
2020	58.15467625899281
2021	57.98201438848921