Year	% of land area
1961	31.8436462205843
1962	32.0190106592991
1963	32.208720007748866
1964	32.37597927409758
1965	32.56353808243314
1966	32.7650889504903
1967	32.95043466278609
1968	33.17619870990655
1969	33.41006389352693
1970	33.66345776869644
1971	33.953713515769856
1972	34.27989942621514
1973	34.59319745244597
1974	34.91225005016006
1975	35.16673714634282
1976	35.513145707133965
1977	35.88111937762098
1978	36.25261406625707
1979	36.57836251900107
1980	36.88656030774171
1981	37.13078315123341
1982	37.46043170957337
1983	37.899961457333674
1984	38.3266954434612
1985	38.85193540687305
1986	39.09194539567925
1987	39.373456265316534
1988	39.559809125877116
1989	39.767162985894885
1990	40.03969834381845
1991	40.129486031351874
1992	34.647028144689
1993	34.67948620806958
1994	34.725906706528505
1995	34.60597279881676
1996	34.59096502103183
1997	34.64210719450687
1998	34.66709433073247
1999	34.7029435843672
2000	34.69953978581508
2001	34.67103203411147
2002	34.69247734751658
2003	34.7131186092712
2004	34.739010319346335
2005	34.75390951412714
2006	34.76217111516639
2007	34.78612270292532
2008	34.679794044265584
2009	34.643762748122434
2010	34.78739494042929
2011	34.7468005365811
2012	34.75468860389372
2013	34.753859257321345
2014	34.68042601288942
2015	34.6868011788715
2016	34.665203780007054
2017	34.65346308499187
2018	34.62903653568632
2019	34.59901427207455
2020	34.66949633392619
2021	34.67054793183708