Year	% of land area
1961	17.05121509109343
1962	17.05121509109343
1963	17.05121509109343
1964	17.05121509109343
1965	17.05121509109343
1966	17.05121509109343
1967	17.112660911241512
1968	17.174106731389596
1969	17.20482964146364
1970	17.296998371685763
1971	17.296998371685763
1972	17.35844419183385
1973	17.450612922055978
1974	17.51205874220406
1975	17.51205874220406
1976	18.126516943684905
1977	18.372300224277243
1978	18.430673753417924
1979	18.3415773142032
1980	18.249408583981076
1981	18.15723985375895
1982	18.06507112353682
1983	17.972902393314694
1984	17.880733663092567
1985	17.25398629758211
1986	17.112660911241512
1987	16.980552397923134
1988	16.77470890042705
1989	16.590371439982796
1990	16.402961688531136
1991	16.49205812774586
1992	16.91603428676764
1993	16.946757196841684
1994	16.786998064456665
1995	16.599588313005007
1996	17.063504255123046
1997	17.413745429967125
1998	17.705613075670527
1999	18.433746044425327
2000	19.93184594611972
2001	21.37323604101707
2002	21.25261632587345
2003	21.224239687812428
2004	20.86464346760409
2005	20.323682940317163
2006	20.294442046707907
2007	20.186973297755937
2008	20.085232358883857
2009	20.143112014886718
2010	20.547472980650763
2011	20.548767252716384
2012	20.421620828375183
2013	20.519647255545102
2014	20.453392304967593
2015	22.345819651991334
2016	22.330217909485718
2017	22.298127331263583
2018	22.180780974319543
2019	21.644455363096586
2020	21.654026908805506
2021	21.654026908805506