Year	% of land area
1961	3.344103392568659
1962	3.344103392568659
1963	3.344103392568659
1964	3.347334410339257
1965	3.347334410339257
1966	3.347334410339257
1967	3.3537964458804526
1968	3.360258481421648
1969	3.360258481421648
1970	3.3667205169628436
1971	3.3667205169628436
1972	3.3731825525040384
1973	3.3764135702746363
1974	3.3796445880452346
1975	3.382875605815832
1976	3.3861066235864294
1977	3.3893376413570278
1978	3.395799676898223
1979	3.395799676898223
1980	3.395799676898223
1981	3.395799676898223
1982	3.395799676898223
1983	3.408723747980614
1984	3.4216478190630046
1985	3.428109854604201
1986	3.4474959612277867
1987	3.45718901453958
1988	3.4668820678513734
1989	3.4798061389337644
1990	3.489499192245557
1991	3.489499192245557
1992	3.4991922455573503
1993	3.463651050080775
1994	3.463651050080775
1995	3.4604200323101777
1996	3.4604200323101777
1997	3.45718901453958
1998	3.4604200323101777
1999	3.4604200323101777
2000	3.7899838449111467
2001	3.7919224555735056
2002	4.11437802907916
2003	4.436187399030694
2004	4.756058158319871
2005	4.733441033925686
2006	4.7269789983844905
2007	4.733441033925686
2008	4.708239095315024
2009	4.6991922455573505
2010	4.663004846526656
2011	4.6423263327948305
2012	4.600323101777059
2013	4.58642972536349
2014	4.587399030694669
2015	4.633279483037157
2016	4.639741518578353
2017	4.691179321486269
2018	4.7169305331179325
2019	4.721809369951535
2020	4.713828756058158
2021	4.737382875605816