Year	% of land area
1961	4.623479342456933
1962	4.6309472739145985
1963	4.659159459421335
1964	4.669116701364889
1965	4.673680437255684
1966	4.701062852600458
1967	4.7413067054556555
1968	4.715168945353827
1969	4.740476935293693
1970	4.829677227704698
1971	4.805613893007775
1972	4.820549755923107
1973	4.871912528948607
1974	4.903587804882097
1975	4.943538924451364
1976	4.9485580657368
1977	4.9324375349056835
1978	4.944075988275791
1979	4.91584047905742
1980	4.867767415381603
1981	4.859986738512174
1982	4.853555165880632
1983	4.915027494277904
1984	4.8834713850734826
1985	4.842640933523543
1986	4.81741236183415
1987	4.788366308902283
1988	4.773013395209725
1989	4.757826458962492
1990	4.757660481517167
1991	4.66898703135231
1992	4.306493832493456
1993	4.1972895033175295
1994	4.190274516978563
1995	4.124479818920851
1996	4.117426703756583
1997	4.1527952240530155
1998	4.2041768463135725
1999	4.242231566070767
2000	4.213471519468968
2001	4.233727905345184
2002	4.1511904957318535
2003	4.128462425228283
2004	4.092789104996895
2005	4.094171227102819
2006	4.054560383913775
2007	4.011033285196155
2008	4.002680768557186
2009	3.9806166148458653
2010	3.965907638968039
2011	3.896625293394643
2012	4.015355012791018
2013	3.935805040583285
2014	3.9641875494332597
2015	3.987086919942466
2016	3.914390717670044
2017	3.9358116622919743
2018	3.9860908473768086
2019	4.033549056338792
2020	3.9717091911499742
2021	3.9855712196175617