Year	% of land area
1961	68.0361374407583
1962	67.75177725118483
1963	67.44372037914692
1964	66.87796208530806
1965	66.56694312796209
1966	66.59063981042654
1967	66.4010663507109
1968	66.19372037914691
1969	65.70497630331754
1970	65.20438388625593
1971	63.28199052132702
1972	62.84656398104266
1973	62.44075829383886
1974	62.1771327014218
1975	61.82168246445497
1976	61.60841232227489
1977	61.19075829383887
1978	60.731635071090054
1979	60.33175355450236
1980	60.3436018957346
1981	60.145142180094794
1982	60.05331753554503
1983	59.502369668246445
1984	59.68305687203791
1985	59.8281990521327
1986	59.774881516587676
1987	59.665284360189574
1988	59.6978672985782
1989	59.416469194312796
1990	59.774881516587676
1991	58.33827014218009
1992	58.16943127962085
1993	58.26125592417062
1994	57.77251184834123
1995	58.19609004739337
1996	57.77843601895734
1997	58.15462085308057
1998	56.74763033175355
1999	58.43009478672986
2000	58.04502369668246
2001	56.95201421800948
2002	57.46741706161137
2003	56.685426540284354
2004	57.742890995260666
2005	57.39632701421801
2006	56.86018957345972
2007	56.70616113744076
2008	57.14751184834124
2009	56.84553809664986
2010	55.50844945152683
2011	55.11269276393832
2012	54.61743772241993
2013	54.84119916889285
2014	54.58889878302167
2015	54.826254826254825
2016	53.9055539055539
2017	54.024354024354025
2018	54.14315414315415
2019	53.95901395901396
2020	53.889218889218895
2021	53.816453816453816