Year	% of land area
1961	55.146014931778375
1962	55.496073299250945
1963	55.52285600758118
1964	55.766202021550455
1965	56.084455922880856
1966	56.218787944349714
1967	56.31608450195566
1968	56.37885647460466
1969	55.957656538129896
1970	56.08508364260736
1971	55.96372449548596
1972	56.086339082060334
1973	56.47075464256279
1974	56.45529181330025
1975	56.60992010592561
1976	56.54394676267152
1977	56.58370234534922
1978	56.90844268385335
1979	56.86931482090215
1980	57.03419586906018
1981	56.87370885898758
1982	57.3611541505979
1983	56.85994087298656
1984	57.319766496631345
1985	57.21087804807622
1986	56.864711542907884
1987	57.18853122581317
1988	56.88149258359605
1989	57.077466682206214
1990	56.91124649863168
1991	56.95656786288425
1992	56.76222583556296
1993	56.8116483020286
1994	56.843395609645704
1995	56.82793130327642
1996	56.77642552406816
1997	56.98161046711425
1998	57.01056937145348
1999	57.03533740685794
2000	57.002763675373956
2001	56.961465690824554
2002	56.94470344443211
2003	56.885826053978626
2004	56.758962109618906
2005	56.72521618873569
2006	56.684763004074455
2007	56.57975240554968
2008	56.49073443909563
2009	56.54726409662484
2010	56.43447726415741
2011	56.59926635110388
2012	56.619576784231725
2013	56.70844802929062
2014	56.718928128943794
2015	56.7309989455214
2016	56.852554328924604
2017	56.834719276535346
2018	56.84503463641616
2019	56.749445722534794
2020	56.800281544279805
2021	56.74151761381265