Year	% of land area
1961	0.5303090213007458
1962	0.5396126883411096
1963	0.5489163553814737
1964	0.5582200224218375
1965	0.5675236894622016
1966	0.5768273565025654
1967	0.5861310235429295
1968	0.6000865241034754
1969	0.6140420246640214
1970	0.6326493587447493
1971	0.6512566928254772
1972	0.6745158604263871
1973	0.697775028027297
1974	0.7256860291483889
1975	0.7535970302694807
1976	0.7815080313905727
1977	0.8094190325116645
1978	0.8326782001125743
1979	0.8559373677134843
1980	0.8791965353143941
1981	0.902455702915304
1982	0.925714870516214
1983	1.0234033744400355
1984	1.0931808772427654
1985	1.1862175476464047
1986	1.2559950504491344
1987	1.3490317208527742
1988	1.4188092236555039
1989	1.4885867264582335
1990	1.5769715633416912
1991	1.6648912168731305
1992	1.6979192348664227
1993	1.708153268610823
1994	1.7058273518507319
1995	1.7002451516265136
1996	1.6960585014583498
1997	1.6928022179942226
1998	1.6918718512901858
1999	1.6718689671534035
2000	1.6709386004493672
2001	1.6746600672655125
2002	1.6746600672655125
2003	1.6746600672655125
2004	1.628141732063693
2005	1.628141732063693
2006	1.6048825644627829
2007	1.60302183105471
2008	1.553247212388763
2009	1.4867259930501606
2010	1.4792830594178696
2011	1.4695142090254874
2012	1.4499765082407232
2013	1.4271825239918314
2014	1.595578897422419
2015	1.623489898543511
2016	1.6174425149672742
2017	1.5993003642385646
2018	1.595578897422419
2019	1.595578897422419
2020	1.595578897422419
2021	1.595578897422419