Year	% of land area
1961	59.483733544143966
1962	59.645135434851824
1963	59.80763529760532
1964	59.96903718831319
1965	60.130439079021045
1966	60.183141737211365
1967	59.90535480966655
1968	60.06785467242004
1969	60.33905376769108
1970	60.55535426068053
1971	60.71785412343401
1972	60.87925601414188
1973	61.04065790484974
1974	61.20315776760323
1975	61.3645596583111
1976	61.52596154901896
1977	61.39420490354316
1978	61.51278588447138
1979	61.85096127452595
1980	62.080437432062986
1981	62.1990184129912
1982	62.31869736596506
1983	62.43727834689329
1984	62.774355764902225
1985	63.113629127002426
1986	63.34200731249382
1987	63.43313899228126
1988	63.64285165299691
1989	63.79327382324846
1990	64.4663306872207
1991	65.25796853212117
1992	66.5327140770996
1993	66.92908198557265
1994	67.98423312142474
1995	70.35695071203487
1996	70.53372421138158
1997	70.70939973868265
1998	71.59985506768997
1999	71.7634529024891
2000	71.9259527652426
2001	72.10053032049804
2002	72.25534437893211
2003	72.41894221373124
2004	72.57924613239346
2005	72.74723585537512
2006	72.9020499138092
2007	73.06564774860831
2008	73.23034355545308
2009	73.39174544616094
2010	73.55753922505133
2011	73.72113705985046
2012	73.88583286669521
2013	74.04943070149434
2014	74.21522448038473
2015	74.3733324549557
2016	74.54242014998297
2017	74.70492001273648
2018	74.87290973571812
2019	75.03760554256289
2020	75.20339932145328
2021	75.36919310034367