Year	% of land area
1961	10.61791731504824
1962	10.549786569991422
1963	10.610342637354423
1964	10.57513493351058
1965	10.565068596182158
1966	10.546774203873644
1967	10.509258749262095
1968	10.736996543191644
1969	10.911059430221352
1970	10.835722080635003
1971	10.703618128591819
1972	10.680147315676932
1973	10.591544473820296
1974	10.57386309565416
1975	10.533355092784804
1976	10.556808130580642
1977	10.57692119144998
1978	10.705197703975282
1979	10.723072502080072
1980	10.745337653518
1981	10.76082127431404
1982	10.770697976202344
1983	10.760145368418335
1984	10.85021828930006
1985	10.838362157805369
1986	10.83675756094922
1987	10.746768563098552
1988	10.688315104991062
1989	10.643562806343828
1990	10.613328624201976
1991	10.598005888418632
1992	10.62345599835211
1993	10.681908839042983
1994	10.651073856437002
1995	10.570768103510604
1996	10.556010605184875
1997	10.561366669759266
1998	10.535286307849276
1999	10.51920819907112
2000	10.521956757155683
2001	10.465414316005063
2002	10.335682056255337
2003	10.214023834634677
2004	10.201898586482486
2005	10.133033870882388
2006	9.980250860856673
2007	9.830473091094893
2008	9.832517350874594
2009	9.871625573557095
2010	9.740458944671612
2011	9.865238598391809
2012	9.834412691760866
2013	9.823199933102595
2014	9.87744680125875
2015	9.858197062253799
2016	9.83243436988477
2017	9.866629503044841
2018	9.860524391430703
2019	9.862528312098075
2020	9.828187438385099
2021	9.89956146530942