Year	% of land area
1961	63.077327664610294
1962	62.89652754188536
1963	62.739468849417236
1964	62.29203420226968
1965	62.09479770475157
1966	61.81172680553577
1967	61.41542754663365
1968	60.59178254310896
1969	60.582651223779415
1970	59.344444322693526
1971	59.578206097529794
1972	59.38096960001169
1973	59.28052508738673
1974	59.247652337800375
1975	59.092419909198156
1976	58.47879525025294
1977	58.27607996113711
1978	58.369219418298435
1979	58.13728390732806
1980	57.932742354346324
1981	57.86882311903953
1982	57.79394630053729
1983	57.6460189273987
1984	57.54192188704192
1985	57.42138847189197
1986	57.335554070194284
1987	57.25885098782613
1988	56.303714985956034
1989	56.140994875503594
1990	55.87052519696256
1991	55.67347132583104
1992	55.489749180920654
1993	55.31990664139117
1994	55.16211744337669
1995	55.0622208099115
1996	54.96378518753904
1997	54.86023602634204
1998	54.751390699933886
1999	54.658433869159154
2000	54.43607814203558
2001	54.264227026099086
2002	54.07685269565186
2003	53.90833906769343
2004	53.79871321683009
2005	53.675507755356975
2006	53.53360472060443
2007	53.33892179261702
2008	53.16359757979534
2009	52.99886587149831
2010	52.82792476399717
2011	52.7408105457514
2012	52.679081812487105
2013	52.54923231736605
2014	52.53608300140442
2015	52.46376176361548
2016	52.44754610022335
2017	52.41006689714496
2018	52.341765332193724
2019	52.27069693200891
2020	52.147546282852744
2021	52.147546282852744