Year	% of land area
1990	43.61545222817966
1991	43.14272215874132
1992	42.66999208930298
1993	42.19726201986463
1994	41.7245319504263
1995	41.25180188098796
1996	40.77907181154961
1997	40.30634174211128
1998	39.83361167267294
1999	39.360881603234596
2000	38.888151533796254
2001	38.490120418387974
2002	38.0920893029797
2003	37.694058187571414
2004	37.29602707216314
2005	36.897995956754855
2006	36.499964841346575
2007	36.101933725938295
2008	35.70390261053002
2009	35.305871495121735
2010	34.907840379713456
2011	34.852913773402484
2012	34.7979871670915
2013	34.74306056078052
2014	34.68813395446955
2015	34.633207348158564
2016	34.81691131229674
2017	35.00061527643491
2018	35.032345961149694
2019	35.06407664586447
2020	35.096930994624955
2021	35.12867715891761