Year	% of land area
1961	0.635144448651091
1962	0.6557014399132045
1963	0.6673531758512447
1964	0.6900324475877869
1965	0.7003525565614795
1966	0.7080510249491131
1967	0.7008935300157456
1968	0.7093410385708248
1969	0.7206598677677779
1970	0.7283583361554116
1971	0.7338512973833446
1972	0.7421739659105162
1973	0.7577872920674898
1974	0.7735175270410082
1975	0.7906877101687576
1976	0.8071961765942323
1977	0.8252152488458847
1978	0.8348698094980402
1979	0.8470004320415891
1980	0.8580906924458972
1981	0.8725101116957762
1982	0.8849320356383126
1983	0.8938167283074299
1984	0.9134379582535133
1985	0.941715001198081
1986	0.9590432729892775
1987	0.9676304220865719
1988	0.9845987285775911
1989	0.994729775089519
1990	1.0082981781094988
1991	1.025010066868284
1992	1.0273297093414722
1993	1.0432357592991648
1994	1.0619772926495152
1995	1.0791415923092005
1996	1.0907302662661622
1997	1.1013070226154715
1998	1.120656770004956
1999	1.1388575272821655
2000	1.1627511705880234
2001	1.182060726201773
2002	1.1990304793197344
2003	1.2195211788598426
2004	1.241982126055714
2005	1.2753344491209482
2006	1.292893229671009
2007	1.3265721402479445
2008	1.3492651394507955
2009	1.3732820819868456
2010	1.412268840839892
2011	1.4322299814246227
2012	1.4423201071713079
2013	1.4753213128444254
2014	1.5088913843822231
2015	1.558951797941901
2016	1.55691687941951
2017	1.585434221935188
2018	1.6502289159000885
2019	1.6751783833105824
2020	1.7009941365784702
2021	1.7161521742356967