Year	% of land area
1961	0.3165377709217246
1962	0.3296149675526409
1963	0.33538285656095385
1964	0.35467545083013846
1965	0.3601450007518145
1966	0.37357025965047386
1967	0.38003427319427285
1968	0.38709496491134554
1969	0.3931611930062954
1970	0.39828268066022837
1971	0.39902852837682057
1972	0.40315555240863066
1973	0.40948034104533243
1974	0.41426697821842673
1975	0.4264081568355386
1976	0.42301192846896635
1977	0.4265921399242109
1978	0.4298242752657511
1979	0.43255915901628517
1980	0.43927205549486875
1981	0.4451396242687418
1982	0.4499629647015019
1983	0.45458740449785945
1984	0.4594604700897201
1985	0.46761539618222164
1986	0.46900770063703895
1987	0.47373159075159776
1988	0.4761681235475281
1989	0.4826323942306086
1990	0.4925774260507324
1991	0.4972999530538911
1992	0.4993313705899614
1993	0.4976376948447292
1994	0.503567357773349
1995	0.5009340530569165
1996	0.5104686035301884
1997	0.5172207943030788
1998	0.5329162841129099
1999	0.5436432744577739
2000	0.555553043746728
2001	0.5686000964567712
2002	0.581468286296456
2003	0.5983161750016185
2004	0.604786603127591
2005	0.6225438543968284
2006	0.6335252213412906
2007	0.6567587384352113
2008	0.6719488733827146
2009	0.6945930248762167
2010	0.727508704268469
2011	0.742348386790913
2012	0.7550896607835743
2013	0.7945915973138622
2014	0.8257427986248248
2015	0.8428006741327669
2016	0.8522290946752953
2017	0.8678155321231945
2018	0.8876277685946268
2019	0.9115165950286842
2020	0.936227835753134
2021	0.9411302451814466