Year	% of land area
1961	38.45099305095137
1962	38.533572518755385
1963	38.59653219842657
1964	38.69286756262933
1965	38.810806738483976
1966	38.883686535750414
1967	38.94029734016064
1968	38.9902947328407
1969	38.94038551898371
1970	39.053452814863796
1971	39.157614049613926
1972	39.26924843961914
1973	39.35948867036411
1974	39.41281835160564
1975	39.484366540961155
1976	38.85348753535384
1977	38.92985083381718
1978	39.03346154478071
1979	39.05954058117855
1980	39.05193511409718
1981	38.94059107602599
1982	39.11052763249203
1983	39.07938269367303
1984	39.26136807358252
1985	39.38486498670477
1986	39.37657612982769
1987	39.53115890161885
1988	39.594290891843826
1989	39.71790067450653
1990	39.688263161307894
1991	39.861398732463094
1992	41.205568472251166
1993	41.13896915084384
1994	41.27950629369759
1995	41.455033359046126
1996	41.5327324803799
1997	42.06437149499394
1998	42.14664161074866
1999	42.25901433667699
2000	42.26279269379049
2001	42.33587414868423
2002	42.37722931526276
2003	41.72936180767411
2004	41.78154358393117
2005	41.13957716392624
2006	41.22419638574173
2007	41.295926221535716
2008	41.317488915247324
2009	41.41070766367081
2010	41.45401335344608
2011	41.54891262219253
2012	41.58027250402514
2013	41.684811872252666
2014	41.7012821824199
2015	41.83336246762327
2016	41.89328974404563
2017	41.954448800237216
2018	42.01721431939349
2019	42.00320679743051
2020	42.04081226474718
2021	42.058380100545136