Year	% of land area
1961	2.7173411035629416
1962	2.6451249926524305
1963	2.6031388816579475
1964	2.5745883261816993
1965	2.6043984649877823
1966	2.611955964966789
1967	2.6455448537623756
1968	2.621192909385575
1969	2.616994298286127
1970	2.6232922149352995
1971	2.678713881448017
1972	2.733295825740845
1973	2.7341355479607343
1974	2.747571103478969
1975	2.8739492975723633
1976	2.977654991728736
1977	2.898721103059108
1978	2.8936827697397702
1979	2.874369158682308
1980	2.886545130870708
1981	2.8907437419701565
1982	2.889064297530377
1983	2.7677244367563207
1984	2.903339575268501
1985	2.9012402697187767
1986	2.925172352985632
1987	2.967998186200005
1988	2.9814337417182397
1989	2.993189852796695
1990	2.973036519519343
1991	3.0481916581994675
1992	3.1749897134028067
1993	3.162813741214406
1994	3.1393015190574953
1995	3.1569356856751787
1996	3.1577754078950684
1997	3.2119374910779515
1998	3.2165559632873446
1999	3.221594296606683
2000	3.2169758243972897
2001	3.1838067967116475
2002	3.1686917967536337
2003	3.1505118106930228
2004	3.146019296816613
2005	3.15357679679562
2006	3.136362491287882
2007	3.135942630177937
2008	3.144339852376834
2009	3.146019296816613
2010	3.149798046806117
2011	3.149798046806117
2012	3.151687421800868
2013	3.1473628523684365
2014	3.136110574621915
2015	3.1330442730758716
2016	3.108734325016868
2017	3.136700044211356
2018	3.149252416614569
2019	3.161804747031688
2020	3.161804747031688
2021	3.161804747031688