Year	% of land area
1961	28.10281537737321
1962	27.932819939128052
1963	27.816348428909123
1964	27.706337749503387
1965	27.557258630312695
1966	27.545506649414243
1967	27.524651021340933
1968	27.54412179157128
1969	27.51747293347761
1970	27.45225771553409
1971	27.383952774913038
1972	27.330268843391007
1973	27.271067549944814
1974	27.215066326414636
1975	27.216556014134156
1976	27.218100323736728
1977	27.20701097800537
1978	27.06670446427409
1979	27.046014357058503
1980	27.02532424984292
1981	27.004910010723545
1982	27.179148300288382
1983	27.17484475798754
1984	27.170541215686697
1985	27.166237673385858
1986	27.161872998714895
1987	26.923253054246043
1988	26.93020493027048
1989	26.937156806294915
1990	26.944108682319353
1991	26.951294847600533
1992	26.8637207190844
1993	26.723083163637675
1994	26.619522280321267
1995	26.56060237233321
1996	26.345314910052654
1997	26.26818219035296
1998	26.253119792300012
1999	26.21576725207348
2000	26.241054782650334
2001	26.272286822432402
2002	26.21176237469083
2003	26.201463141986423
2004	26.19118045866505
2005	26.18090329180468
2006	26.11951611369294
2007	26.085468516343397
2008	25.966595160266646
2009	25.82684519858153
2010	25.68709523689642
2011	25.5471078774966
2012	25.443092002545786
2013	25.477152843936288
2014	25.511211134681577
2015	25.54531911332064
2016	25.57904615144075
2017	25.599106468127093
2018	25.600298977577733
2019	25.589179931125955
2020	25.55768884822579
2021	25.802696483653648