Year	% of land area
1961	52.35918806291168
1962	52.82968140879151
1963	53.434601424922704
1964	54.01711699601201
1965	54.711654792310796
1966	55.4241161446431
1967	55.872205045481024
1968	56.54433839673791
1969	56.972263297038126
1970	57.59062598019447
1971	58.1014473271497
1972	58.63243267464265
1973	59.209052207035626
1974	59.66838449473448
1975	60.311449697512884
1976	60.833520053775494
1977	61.61774591082232
1978	62.554335648666815
1979	62.74703114496975
1980	64.82186869818509
1981	65.18037194712078
1982	65.37530808872955
1983	65.59041003809098
1984	65.83912166704012
1985	65.87049070132198
1986	66.09231458660093
1987	66.47098364328927
1988	66.64575397714542
1989	67.3627604750168
1990	67.98790051534841
1991	68.0147882590186
1992	68.59959668384494
1993	68.81245798790052
1994	69.37934125028008
1995	68.89760250952274
1996	69.38382254089179
1997	69.22473672417657
1998	69.40622899395026
1999	68.77212637239525
2000	68.68025991485548
2001	68.04839793860631
2002	67.85346179699754
2003	69.18216446336545
2004	67.3112256329823
2005	67.1947120770782
2006	67.09836432892673
2007	67.1297333632086
2008	67.17678691463142
2009	67.22518485323774
2010	67.1931436253641
2011	67.45193815818956
2012	68.12233923369931
2013	68.53013667936365
2014	67.40421241317499
2015	67.3246695048174
2016	69.17992381805959
2017	69.5643024871163
2018	68.39750660990364
2019	66.34978041676003
2020	68.02151019493614
2021	67.87138695944432