Year	% of land area
1961	60.04796163069545
1962	60.04796163069545
1963	60.043165467625904
1964	59.6546762589928
1965	59.21822541966427
1966	58.68105515587529
1967	58.196642685851316
1968	57.66426858513189
1969	57.32374100719424
1970	56.983213429256594
1971	58.80095923261391
1972	58.695443645083934
1973	58.78657074340528
1974	59.02158273381295
1975	59.256594724220626
1976	58.99613899613899
1977	59.18436293436293
1978	60.91698841698842
1979	63.07915057915058
1980	63.31563706563706
1981	61.138996138996134
1982	59.49324324324324
1983	59.05405405405405
1984	59.29054054054054
1985	60.00482625482626
1986	60.72393822393822
1987	60.477799227799224
1988	61.196911196911195
1989	60.9507722007722
1990	61.33204633204633
1991	61.954633204633204
1992	62.81370656370656
1993	62.56756756756757
1994	62.46621621621622
1995	62.268339768339764
1996	60.13996138996139
1997	59.89382239382239
1998	61.28378378378378
1999	62.53378378378378
2000	62.09942084942085
2001	61.66505791505792
2002	60.98938223938224
2003	60.55501930501931
2004	61.809845559845556
2005	58.81274131274131
2006	58.73069498069498
2007	59.90830115830116
2008	59.72490347490348
2009	59.54150579150579
2010	59.35810810810811
2011	59.16988416988417
2012	58.98648648648649
2013	58.8030888030888
2014	58.6003861003861
2015	59.02509652509652
2016	58.59555984555984
2017	58.16602316602316
2018	57.70752895752895
2019	57.70752895752895
2020	57.70752895752895
2021	57.70752895752895