Year	% of land area
1961	0.3197293080326964
1962	0.3219217375734921
1963	0.32374876219082177
1964	0.3259411917316174
1965	0.3277682163489471
1966	0.3299606458897427
1967	0.3317876705070724
1968	0.33398010004786804
1969	0.33580712466519774
1970	0.33799955420599337
1971	0.340191983746789
1972	0.3420190083641187
1973	0.3442114379049143
1974	0.346038462522244
1975	0.34823089206303964
1976	0.35005791668036934
1977	0.35225034622116497
1978	0.35407737083849466
1979	0.3562698003792903
1980	0.3584622299200859
1981	0.3602892545374156
1982	0.36248168407821124
1983	0.3646741136190069
1984	0.36650113823633657
1985	0.36832816285366626
1986	0.37052059239446195
1987	0.37234761701179164
1988	0.37454004655258727
1989	0.37271302193525757
1990	0.37271302193525757
1991	0.37271302193525757
1992	0.37271302193525757
1993	0.37271302193525757
1994	0.37271302193525757
1995	0.37271302193525757
1996	0.37271302193525757
1997	0.3708859973179279
1998	0.3708859973179279
1999	0.3654049234659388
2000	0.3654049234659388
2001	0.3654049234659388
2002	0.3654049234659388
2003	0.3654049234659388
2004	0.3654049234659388
2005	0.3654049234659388
2006	0.3654049234659388
2007	0.3654049234659388
2008	0.3654049234659388
2009	0.3654049234659388
2010	0.3654049234659388
2011	0.3654049234659388
2012	0.3654049234659388
2013	0.3654049234659388
2014	0.3654049234659388
2015	0.3654049234659388
2016	0.3654049234659388
2017	0.3654049234659388
2018	0.39025245826162264
2019	0.39025245826162264
2020	0.39025245826162264
2021	0.39025245826162264