Year	% of land area
1961	28.433055136830056
1962	28.403640947635367
1963	28.446491873102687
1964	28.275139490272757
1965	28.132180123718996
1966	27.95535803772323
1967	27.823386671433703
1968	27.73772502987847
1969	27.89964553898689
1970	27.611821110962794
1971	27.19173565398645
1972	27.21668998687651
1973	27.089039724399914
1974	27.00293659557156
1975	26.869396939653704
1976	26.809614644098822
1977	26.85690690065983
1978	26.918916473358436
1979	27.00444189362102
1980	26.92478070719011
1981	26.932219703044254
1982	26.686464160720284
1983	26.491524787330214
1984	26.71045024489179
1985	26.73271842163986
1986	26.72603680557765
1987	26.840764434018762
1988	26.6999545362487
1989	26.529680275571017
1990	26.437983073640705
1991	26.29698266642339
1992	13.53118787787471
1993	13.533617922744677
1994	13.46165607487716
1995	13.377516272338486
1996	13.270253191794747
1997	13.295307358258663
1998	13.181755889547825
1999	13.104662171056404
2000	12.975365410169843
2001	12.81507728437882
2002	12.713748692227128
2003	12.613658748591245
2004	12.597546772856061
2005	12.55775384143651
2006	12.56192014421926
2007	12.467968512239258
2008	12.47269457124818
2009	12.459027454376649
2010	12.419562686521962
2011	12.399327071273419
2012	12.414502725891772
2013	12.39885270325139
2014	12.400760153205384
2015	12.38574450713036
2016	12.367393108781876
2017	12.359486105978764
2018	12.330586412611861
2019	12.334111421693695
2020	12.31311474270445
2021	12.328911016540996