Year	% of land area
1961	0.4890036358007938
1962	0.49247164352366707
1963	0.4965819750608378
1964	0.4992155906363144
1965	0.5002502584456737
1966	0.5023315578073976
1967	0.5068905848011112
1968	0.5048991255034077
1969	0.5116064384127883
1970	0.5153661465533697
1971	0.5164370513412647
1972	0.5173109081537856
1973	0.5210869242979823
1974	0.5245991722680299
1975	0.5245304785049393
1976	0.524142035474686
1977	0.5210091203372162
1978	0.5242970572367813
1979	0.5228143799467653
1980	0.5182304867363415
1981	0.5165687521732125
1982	0.5203318864484127
1983	0.5250549333541249
1984	0.5236252278233154
1985	0.520241269820574
1986	0.5172060589536607
1987	0.5137778673951663
1988	0.5139765257235085
1989	0.5111975561742002
1990	0.5145799782809294
1991	0.5071673169832144
1992	0.5385499637845385
1993	0.5362041849922465
1994	0.5343735656129883
1995	0.5310838818937659
1996	0.5319445230768776
1997	0.5407629465626344
1998	0.5457565369181823
1999	0.5550270248418497
2000	0.5531238486950913
2001	0.5538955365318218
2002	0.5425144976224939
2003	0.5404521805903286
2004	0.5364958949674061
2005	0.5354799815177774
2006	0.5316348291352682
2007	0.5307449236802912
2008	0.5297738577374396
2009	0.5272647546441296
2010	0.5266269771389108
2011	0.5205909933629648
2012	0.5296473672558139
2013	0.5243025889880776
2014	0.5252036272022217
2015	0.528065979263154
2016	0.5217584081496792
2017	0.5289518165157554
2018	0.5321804909517689
2019	0.5357528113848836
2020	0.5301638063365827
2021	0.5346571604325548