Year	% of land area
1961	0.44141689373297005
1962	0.4450499545867393
1963	0.4532243415077203
1964	0.4532243415077203
1965	0.48138056312443234
1966	0.544959128065395
1967	0.5903723887375113
1968	0.6539509536784741
1969	0.6539509536784741
1970	0.6539509536784741
1971	0.6630336058128974
1972	0.6630336058128974
1973	0.6630336058128974
1974	0.6630336058128974
1975	0.6630336058128974
1976	0.6630336058128974
1977	0.6630336058128974
1978	0.662125340599455
1979	0.6557674841053587
1980	0.6494096276112624
1981	0.6448683015440508
1982	0.6403269754768393
1983	0.633969118982743
1984	0.6267029972752043
1985	0.6267029972752043
1986	0.6221616712079927
1987	0.6176203451407811
1988	0.6130790190735695
1989	0.6085376930063578
1990	0.6012715712988193
1991	0.5976385104450499
1992	0.594913714804723
1993	0.54
1994	0.54
1995	0.5599999999999999
1996	0.573
1997	0.592
1998	0.5579999999999999
1999	0.676
2000	0.662
2001	0.697
2002	0.645
2003	0.679
2004	0.653023006486963
2005	0.6804892426320067
2006	0.7292135026300565
2007	0.9205842703997392
2008	0.8036730456166344
2009	0.9188467041631496
2010	0.9906333297155426
2011	1.003034746308292
2012	1.0118892359956448
2013	1.0881006686070256
2014	1.164337994517407
2015	1.240541587033164
2016	1.3167239342484103
2017	1.3919596603373867
2018	1.5205198014967778
2019	1.7703806418861119
2020	2.021139533443641
2021	2.021139533443641