Year	% of land area
1961	18.77917814250539
1962	19.22269787297174
1963	19.666217603438085
1964	20.109737333904434
1965	20.55325706437078
1966	20.996776794837128
1967	21.440296525303477
1968	21.883816255769826
1969	22.32733598623617
1970	22.771573579767747
1971	23.191044897548977
1972	23.610516215330204
1973	24.029987533111434
1974	24.449458850892665
1975	24.869049812518096
1976	25.457817169848795
1977	26.04658452717949
1978	26.63535188451019
1979	27.22411924184089
1980	27.81925260883402
1981	28.04616816660166
1982	28.273108610288894
1983	28.500049053976124
1984	28.726989497663357
1985	28.953655598015825
1986	28.783820323660525
1987	28.613949993658878
1988	28.444079663657224
1989	28.274209333655577
1990	28.104339003653923
1991	27.934468673652272
1992	27.764598343650622
1993	27.594728013648968
1994	27.424857683647318
1995	27.25546592902249
1996	27.267872995666497
1997	27.280280062310514
1998	27.29268712895453
1999	27.305094195598546
2000	27.317501262242555
2001	27.32990832888657
2002	27.342315395530587
2003	27.354722462174596
2004	27.367129528818612
2005	27.37953659546263
2006	27.392577774480927
2007	27.47881705738358
2008	27.565056340286237
2009	27.651295623188894
2010	27.73753490609155
2011	27.823774188994204
2012	27.910013471896853
2013	27.99625275479951
2014	28.082492037702167
2015	28.168731320604824
2016	28.25497060350748
2017	28.341066313797086
2018	28.415628477149223
2019	28.49012950249697
2020	28.564618563460293
2021	28.63909446360075