Year	% of land area
1961	69.12335143522111
1962	69.06128782001552
1963	69.98448409619861
1964	69.75174553917766
1965	67.32350659425911
1966	70.51978277734679
1967	70.69821567106284
1968	70.93095422808379
1969	70.93871217998449
1970	71.02404965089217
1971	71.02404965089217
1972	71.06283941039565
1973	70.93095422808379
1974	70.91543832428239
1975	70.73700543056634
1976	70.71373157486424
1977	70.69045771916214
1978	71.17920868890613
1979	71.22575640031032
1980	71.21799844840963
1981	71.41970519782778
1982	71.41970519782778
1983	71.23351435221102
1984	71.44297905352987
1985	71.24903025601242
1986	71.21799844840963
1987	71.19472459270753
1988	71.21024049650893
1989	71.48952676493406
1990	71.54383242823894
1991	71.09387121799845
1992	71.11714507370054
1993	71.06283941039565
1994	71.14041892940264
1995	71.09387121799845
1996	71.15593483320404
1997	69.70519782777347
1998	68.13033359193173
1999	67.26144297905353
2000	66.16757176105507
2001	65.46159813809155
2002	64.7245927075252
2003	64.01861908456168
2004	62.684251357641585
2005	62.10240496508922
2006	61.000775795190066
2007	60.14740108611326
2008	59.402637703646235
2009	58.650116369278514
2010	58.09930178432894
2011	57.377812257563996
2012	56.501163692785106
2013	55.49262994569434
2014	48.10705973622964
2015	48.09154383242824
2016	47.602792862684254
2017	46.963078355314195
2018	46.110864235841746
2019	45.51736229635377
2020	45.51736229635377
2021	45.51736229635377