Year	% of land area
1961	66.48925527231982
1962	66.49325703309457
1963	66.30317339629437
1964	65.53483532754412
1965	65.41678338468925
1966	64.34030973628396
1967	64.79250870382968
1968	64.34631237744608
1969	65.0826363599984
1970	64.26627716195125
1971	65.39677458081556
1972	65.16467245588059
1973	64.5884189043179
1974	64.18809404702351
1975	63.88927806576867
1976	63.08625417859359
1977	63.23817912479481
1978	63.01523432026105
1979	62.76774632662049
1980	62.54229483252247
1981	62.47947783606295
1982	62.449445401033124
1983	61.652283603307765
1984	61.324683645683166
1985	61.49287201665866
1986	61.28864328047413
1987	61.27062309786962
1988	61.22457152010251
1989	61.47084734903091
1990	61.012333813871535
1991	60.810107320198625
1992	60.625901009130224
1993	60.133349351273424
1994	60.43368572801538
1995	59.50464520262694
1996	60.3455870575044
1997	60.185407656575364
1998	59.983181162902454
1999	59.62277751081211
2000	59.65130260521042
2001	59.215277220572894
2002	58.951186277653086
2003	58.398269265439396
2004	58.23750951560559
2005	58.434350517942654
2006	57.342979678544225
2007	56.10787201218168
2008	56.41940657578187
2009	56.090322063129186
2010	55.08889822203555
2011	54.04096983275986
2012	53.86137822114711
2013	53.4439535395134
2014	53.13368385278183
2015	53.18906218416086
2016	52.57724735969765
2017	52.638713827628145
2018	52.408209711445984
2019	52.45849172587285
2020	52.33167922328408
2021	52.484894120832195