Year	% of land area
1961	6.063903975572196
1962	6.117967648604078
1963	6.15897443456411
1964	6.190647586406373
1965	6.228084129807695
1966	6.2314503585059065
1967	6.263786555394787
1968	6.315147044775075
1969	6.369210717806957
1970	6.345749123849726
1971	6.380890511320449
1972	6.4132777116744535
1973	6.385786843972393
1974	6.37153385492921
1975	6.37176585944779
1976	6.415681634805287
1977	6.433329553822353
1978	6.45684311066301
1979	6.497749558789273
1980	6.521161104537346
1981	6.5034621799739885
1982	6.520396021342965
1983	6.5183047939449885
1984	6.50738960703848
1985	6.528250875471948
1986	6.543042483896657
1987	6.527689814462735
1988	6.551764432312606
1989	6.535340646406549
1990	6.630108951417268
1991	6.75293323556349
1992	8.295129763829191
1993	8.44449114361327
1994	8.47489991177523
1995	8.678908389755028
1996	8.794585325499565
1997	8.816310976040205
1998	8.838136280097123
1999	8.87467172325531
2000	8.875098421222969
2001	8.932628352574696
2002	8.98913124690657
2003	9.18560764749731
2004	9.175269882552488
2005	9.31593370515348
2006	9.383450009578404
2007	9.520123243673783
2008	9.505713090958112
2009	9.657020556369526
2010	9.76652624590933
2011	9.91456379832753
2012	10.090606280550855
2013	10.218627525468705
2014	10.293573957073523
2015	10.339555150956455
2016	10.42233335509802
2017	10.503955529626776
2018	10.577269142621088
2019	10.611030031433126
2020	10.628524458335313
2021	10.64972214117606