Year	% of land area
1990	66.44273394940562
1991	66.14587238922829
1992	65.84901082905097
1993	65.55214926887365
1994	65.25528770869632
1995	64.958426148519
1996	64.66156458834168
1997	64.36470302816434
1998	64.06784146798702
1999	63.77097990780971
2000	63.47411834763239
2001	63.17725678745506
2002	62.88039522727774
2003	62.58353366710042
2004	62.28667210692309
2005	61.98981054674577
2006	61.69294898656845
2007	61.39608742639112
2008	61.0992258662138
2009	60.80236430603648
2010	60.505502745859154
2011	60.01968372995743
2012	59.53386471405571
2013	59.048045698153985
2014	58.56222668225226
2015	58.07640766635054
2016	57.59058688604133
2017	57.10477051675085
2018	56.61894973644163
2019	56.133128956132424
2020	55.64731258684192
2021	55.16149326216889