Year	% of land area
1961	0.30864197530864196
1962	0.3162315320785266
1963	0.3263509411050395
1964	0.3288807933616677
1965	0.38200769075086016
1966	0.39212709977737303
1967	0.40224650880388585
1968	0.4148957700870269
1969	0.4300748836267962
1970	0.42501517911353975
1971	0.4199554746002834
1972	0.4300748836267962
1973	0.43766444039668084
1974	0.44525399716656544
1975	0.4907913377858733
1976	0.49332119004250147
1977	0.49838089455575796
1978	0.49838089455575796
1979	0.5009270477078559
1980	0.555550636486746
1981	0.553210565181611
1982	0.556899023519867
1983	0.5554241461459278
1984	0.5540038033038703
1985	0.5773678832711383
1986	0.5796789441662376
1987	0.581635825619804
1988	0.5818319714256152
1989	0.5941634523753206
1990	0.5885360392438312
1991	0.5839837993794484
1992	0.5884046392776218
1993	0.5864049415234339
1994	0.5929254515414908
1995	0.595416050779073
1996	0.591401829173486
1997	0.5786263279672191
1998	0.5916457207592801
1999	0.5866392745820346
2000	0.6042873493674573
2001	0.6049056787094698
2002	0.6072901896881059
2003	0.588040202614798
2004	0.5887315000844917
2005	0.5912321816148656
2006	0.5908532048022276
2007	0.5927113285024277
2008	0.5954787849357888
2009	0.6071950920265272
2010	0.6078597735315202
2011	0.610215074037347
2012	0.6159592719462539
2013	0.6226325203938465
2014	0.6463417915123978
2015	0.6279512926145963
2016	0.6339745525331419
2017	0.6303399955909483
2018	0.638363355971696
2019	0.6332127129512476
2020	0.6377078195872753
2021	0.6384721901976809