Year	% of land area
1961	0.702814773166532
1962	0.7115999578311136
1963	0.7203851424956952
1964	0.7291703271602769
1965	0.7379555118248585
1966	0.7467406964894402
1967	0.7555258811540219
1968	0.7643110658186035
1969	0.7730962504831852
1970	0.7818814351477669
1971	0.7906666198123484
1972	0.7994518044769302
1973	0.8082369891415118
1974	0.8170221738060933
1975	0.8293214323365078
1976	0.8398636539340056
1977	0.8433777277998383
1978	0.8433777277998383
1979	0.8433777277998383
1980	0.8433777277998383
1981	0.8433777277998383
1982	0.8433777277998383
1983	0.8433777277998383
1984	0.8433777277998383
1985	0.8433777277998383
1986	0.8433777277998383
1987	0.8433777277998383
1988	0.8433777277998383
1989	0.8433777277998383
1990	0.8433777277998383
1991	0.8433777277998383
1992	0.8433777277998383
1993	0.8433777277998383
1994	0.8433777277998383
1995	0.8433777277998383
1996	0.8433777277998383
1997	0.8433777277998383
1998	0.8433777277998383
1999	0.8433777277998383
2000	0.8433777277998383
2001	0.7221421794286116
2002	0.7502547703552729
2003	0.7520118072881892
2004	0.7625540288856871
2005	0.7695821766173525
2006	0.7801243982148505
2007	0.8258073584706751
2008	0.8521629124644201
2009	0.8521629124644201
2010	0.8960888357873283
2011	0.915416242049408
2012	0.9347436483114875
2013	0.9540710545735671
2014	0.9733984608356467
2015	0.9944829040306427
2016	1.0138103102927223
2017	1.033137716554802
2018	1.0524651228168818
2019	1.0717925290789612
2020	1.0717925290789612
2021	1.0717925290789612