Year	% of land area
1961	34.89640132540506
1962	34.947010915182304
1963	35.034820291753604
1964	35.089800483984625
1965	35.14209871561901
1966	35.177063535249204
1967	35.208204077732354
1968	35.278382046677635
1969	35.31235354756834
1970	35.33296491141285
1971	35.36802906291701
1972	35.41744667020686
1973	35.41174502064216
1974	35.39492108025161
1975	35.43878569111209
1976	35.466386148931015
1977	35.475127701164475
1978	35.545358126494634
1979	35.54396742500295
1980	35.585489798111865
1981	35.631929294352105
1982	35.65425998687575
1983	35.706093418187315
1984	35.71277871892949
1985	35.894990415086646
1986	36.1040724507796
1987	36.21764309473995
1988	36.442221518483116
1989	36.567017110197796
1990	36.63196237318044
1991	36.718888169918294
1992	36.82076203090894
1993	36.15303996419142
1994	36.36353378760987
1995	36.54588710843815
1996	36.723677637593774
1997	36.901098242090235
1998	37.01989062245908
1999	37.21950721329237
2000	37.3984343934221
2001	37.57431262874711
2002	37.67370425650406
2003	37.98609802748536
2004	37.80757142616816
2005	38.2009557989872
2006	38.36419805017516
2007	38.5418286537784
2008	38.67579332949739
2009	38.913404122356866
2010	39.11449419496906
2011	39.29212797193456
2012	39.33998841754582
2013	39.53957383937336
2014	39.660517208022576
2015	39.77079217887689
2016	39.90362107047778
2017	40.03618711595414
2018	40.13336790474686
2019	40.1911914374982
2020	40.2609349549526
2021	40.30346394503234