Year	% of land area
1961	4.3469143211538634
1962	4.4007699855662805
1963	4.4594897090550525
1964	4.51535117102473
1965	4.567100748002025
1966	4.645577577429803
1967	4.705550924391862
1968	4.803534135063989
1969	4.8335208085450185
1970	4.808047179567823
1971	4.875893281942125
1972	4.966806056224913
1973	5.043689414884783
1974	5.12003622771258
1975	5.194711842125585
1976	5.355213912686272
1977	5.513776608019516
1978	5.663413518727771
1979	5.801702630431684
1980	5.956581885609709
1981	6.01287890169306
1982	6.074647158736246
1983	6.155420413845835
1984	6.215388455345151
1985	6.307108755582157
1986	6.271850820013447
1987	6.256917567206522
1988	6.227280756421386
1989	6.208274715336069
1990	6.190467143098986
1991	6.167795492272835
1992	6.110523689767663
1993	6.065592616268527
1994	6.030931262446024
1995	6.024570682383089
1996	6.06932806314597
1997	6.130409191363483
1998	6.205171075773621
1999	6.252479708372636
2000	6.297835909591982
2001	6.329638074059017
2002	6.3609380749830065
2003	6.5221084079488865
2004	6.623047633902243
2005	6.753322045923114
2006	6.87316005437883
2007	6.995944285803815
2008	6.968028885941048
2009	6.9514283481787755
2010	7.154944863900267
2011	7.222165248408729
2012	7.299798148323721
2013	7.317240772552189
2014	7.32126813827786
2015	7.4147002733635
2016	7.387709805833375
2017	7.3563621593326145
2018	7.389964668140242
2019	7.411175956963731
2020	7.5519143643705045
2021	7.614809202351485