Year	% of land area
1961	0.5218122465130082
1962	0.5218122465130082
1963	0.5242852903353448
1964	0.5267583341576813
1965	0.5242852903353448
1966	0.5292313779800178
1967	0.5193392026906717
1968	0.5242852903353448
1969	0.5292313779800178
1970	0.5292313779800178
1971	0.5335968379446641
1972	0.54100790513834
1973	0.54100790513834
1974	0.5400197628458498
1975	0.5408208623499777
1976	0.5408208623499777
1977	0.5408208623499777
1978	0.5408208623499777
1979	0.546994616486393
1980	0.5458811905644065
1981	0.5520563171545017
1982	0.5532913424725207
1983	0.5397060639743114
1984	0.5458811905644065
1985	0.5520563171545017
1986	0.560454489317031
1987	0.5711992095837964
1988	0.575521798196863
1989	0.5749042855378536
1990	0.5965172286031863
1991	0.5983697665802149
1992	0.6076324564653576
1993	0.6144250957144621
1994	0.636038038779795
1995	0.6255403235766334
1996	0.6268988514264543
1997	0.6230702729405952
1998	0.6063974311473386
1999	0.6156601210324811
2000	0.6135605779918488
2001	0.6073854514017537
2002	0.5977522539212053
2003	0.5910831172039027
2004	0.5854761022600964
2005	0.5773249351611708
2006	0.5755958997159442
2007	0.575521798196863
2008	0.5483512412004447
2009	0.5411880943559343
2010	0.4898110411263431
2011	0.4853649499814746
2012	0.47869581326417193
2013	0.47869581326417193
2014	0.4764727676917377
2015	0.47424972211930344
2016	0.47424972211930344
2017	0.47424972211930344
2018	0.47424972211930344
2019	0.4717796714832654
2020	0.4717796714832654
2021	0.4717796714832654