Year	% of land area
1961	0.7764613660825789
1962	0.7795202748484686
1963	0.7817768468888792
1964	0.7845850254280566
1965	0.7857383844709331
1966	0.7884462709194258
1967	0.7905524048238088
1968	0.7936113135896986
1969	0.79772328930778
1970	0.8083542509203805
1971	0.8180645337282882
1972	0.8260877239573262
1973	0.8350636680260626
1974	0.8418633217451722
1975	0.8489980008356094
1976	0.8724212100549378
1977	0.8991484491030629
1978	0.9253742390133246
1979	0.9517755361218385
1980	0.9828447458323372
1981	0.9980637958507103
1982	0.9980888684207571
1983	1.0016241007973479
1984	1.004056140091882
1985	0.9905921699767808
1986	0.9906122280328182
1987	0.9977002435850325
1988	0.9933250801118758
1989	0.9904542708415237
1990	0.9864301233490214
1991	0.9952431317204516
1992	0.9951804502953349
1993	0.9946664626093766
1994	1.0089402767369875
1995	0.971374045035952
1996	0.9721538019644058
1997	0.9966973407831627
1998	1.025704401889118
1999	1.0428157957322903
2000	1.0638641911229454
2001	1.0846288612745278
2002	1.0970876633654776
2003	1.0897710673773624
2004	1.1436904126781091
2005	1.174207196356747
2006	1.1919839635481866
2007	1.1892858118498926
2008	1.1789414909344513
2009	1.1656393971727508
2010	1.1586144104701743
2011	1.1601112745279214
2012	1.146894549422225
2013	1.1412433452621802
2014	1.1365136220754133
2015	1.1391532500809003
2016	1.1203701304427387
2017	1.1062470861347116
2018	1.1277449256463161
2019	1.1384432532555993
2020	1.1504180524452419
2021	1.1614053910237054