Year	% of land area
1961	0.31431061979691527
1962	0.3182484521633914
1963	0.3263926054667853
1964	0.33587920162238694
1965	0.34008552255930463
1966	0.3422334311228371
1967	0.3485876606232873
1968	0.35118305013755563
1969	0.36818732626552086
1970	0.3863550528653995
1971	0.39467819854908776
1972	0.40801313088101837
1973	0.4185751797537414
1974	0.42358698434348047
1975	0.4251084250225084
1976	0.43575850977570385
1977	0.4462296015078372
1978	0.4465710584404612
1979	0.4506836247444174
1980	0.451041239205631
1981	0.4612332513502181
1982	0.4759848478752784
1983	0.5009284565449258
1984	0.5216700952953136
1985	0.5334713725153618
1986	0.54527264973541
1987	0.5599348426451669
1988	0.5848407353354667
1989	0.5989440375611998
1990	0.6148325679167727
1991	0.6205556094966876
1992	0.6286605055116357
1993	0.6236721968600378
1994	0.6331143525219909
1995	0.6440797238614854
1996	0.658332034294622
1997	0.6607371116802138
1998	0.6682195746576105
1999	0.6797104999443269
2000	0.6883411646809932
2001	0.6923041977508073
2002	0.7164164346954682
2003	0.7272678684526286
2004	0.7406561162153061
2005	0.795678273875007
2006	0.8100859334427803
2007	0.8272756020541325
2008	0.8223479800751102
2009	0.8080303644536314
2010	0.8475956378508865
2011	0.8677972498600499
2012	0.8731856392528278
2013	0.907406612115446
2014	0.9151919941115563
2015	0.912583385330597
2016	0.9310261073611903
2017	0.9332098550702415
2018	0.9309940272371963
2019	0.9310611661495842
2020	0.9084624129499332
2021	0.9425302381592134