Year	% of land area
1961	0.38050884642440086
1962	0.3852681089940776
1963	0.3949027137083013
1964	0.405930273320967
1965	0.4112699337649946
1966	0.41370760483726804
1967	0.42160101592843924
1968	0.42461908487506356
1969	0.4459777266511739
1970	0.46872932332572625
1971	0.47859608718969027
1972	0.4956597846956045
1973	0.5086630588967281
1974	0.5137705839061887
1975	0.5178333878909869
1976	0.530253960073084
1977	0.5440674936213977
1978	0.5442996538491005
1979	0.5491750186308583
1980	0.5491750186308583
1981	0.5615955908129555
1982	0.5795880084599186
1983	0.6130190812491149
1984	0.6392531869795258
1985	0.6539953614386504
1986	0.6687375358977752
1987	0.6877746745694008
1988	0.7208575070170429
1989	0.7379212837531951
1990	0.7570745025386721
1991	0.763320336377276
1992	0.7725818252542279
1993	0.7642464852649712
1994	0.7753602719173134
1995	0.788569470428066
1996	0.8058189934613889
1997	0.8073239854038935
1998	0.8154277881712264
1999	0.812417804286217
2000	0.8207531442754737
2001	0.8261942689906829
2002	0.8571044881175097
2003	0.8707959151304799
2004	0.8887425023530542
2005	0.9603239747571983
2006	0.97845856048494
2007	0.9991687679010116
2008	0.9920025747356381
2009	0.9934952815603912
2010	1.0495109585582831
2011	1.0733203169331322
2012	1.078543089611662
2013	1.1234885469344307
2014	1.1421450300101863
2015	1.1373620755086034
2016	1.1607203138735775
2017	1.1630061576284745
2018	1.1584798087430141
2019	1.1558255395898143
2020	1.1253760796808556
2021	1.1710601781957979