Year	% of land area
1961	0.85136891159206
1962	0.8737733566339562
1963	0.8961778016758525
1964	0.9185822467177487
1965	0.9409866917596451
1966	0.9813146928350583
1967	0.9813146928350583
1968	0.9813146928350583
1969	0.9611506922973517
1970	0.9611506922973517
1971	0.9611506922973517
1972	0.9835551373392482
1973	0.9634774815146763
1974	0.9634774815146763
1975	0.9500336096795877
1976	0.9746807080439167
1977	1.008290387631638
1978	1.0306968406901187
1979	1.120322652924042
1980	1.120322652924042
1981	1.120322652924042
1982	1.1427291059825229
1983	1.2323549182164464
1984	1.4564194488012547
1985	1.3892000896258123
1986	1.4340129957427739
1987	1.3443871835088506
1988	1.5012323549182165
1989	1.5841362312345957
1990	1.6491149451041898
1991	1.6535962357158862
1992	1.7521846291732017
1993	1.8194039883486441
1994	1.8821420569123906
1995	1.8552543132422137
1996	1.9493614160878334
1997	2.050190454850997
1998	2.1129285234147437
1999	1.9605646426170737
2000	1.9829710956755546
2001	1.9762491597580103
2002	1.9740085144521622
2003	1.8395697961012771
2004	1.861976249159758
2005	1.942639480170289
2006	1.9762491597580103
2007	2.0053775487340353
2008	2.08155948913287
2009	2.157741429531705
2010	2.820972440062738
2011	2.9128388976025095
2012	3.0383150347300023
2013	3.2646202106206585
2014	3.319291956083352
2015	3.472328030472776
2016	3.7060273358727316
2017	3.6472977817611474
2018	3.750024647098364
2019	3.838097692135335
2020	3.885278960340578
2021	3.986107999103742