Year	% of land area
1961	26.285046728971963
1962	27.258566978193144
1963	28.19314641744548
1964	28.971962616822427
1965	29.439252336448597
1966	29.32242990654206
1967	30.68535825545171
1968	31.15264797507788
1969	38.62928348909657
1970	36.60436137071651
1971	36.176012461059194
1972	34.890965732087224
1973	36.21495327102804
1974	36.21495327102804
1975	36.21495327102804
1976	36.40965732087228
1977	36.68224299065421
1978	36.40965732087228
1979	36.21495327102804
1980	36.21495327102804
1981	36.21495327102804
1982	36.21495327102804
1983	36.21495327102804
1984	36.21495327102804
1985	36.21495327102804
1986	36.21495327102804
1987	36.21495327102804
1988	36.21495327102804
1989	36.21495327102804
1990	36.21495327102804
1991	36.21495327102804
1992	36.21495327102804
1993	36.21495327102804
1994	36.21495327102804
1995	36.60436137071651
1996	36.60436137071651
1997	36.993769470404985
1998	36.993769470404985
1999	37.38317757009346
2000	37.38317757009346
2001	37.967289719626166
2002	38.39563862928349
2003	38.55140186915888
2004	38.35669781931464
2005	37.22741433021807
2006	36.56542056074766
2007	36.68224299065421
2008	36.79906542056075
2009	36.915887850467286
2010	36.993769470404985
2011	38.940809968847354
2012	39.99221183800623
2013	41.04361370716511
2014	42.09501557632399
2015	43.14641744548287
2016	44.19781931464175
2017	45.24922118380063
2018	46.3006230529595
2019	47.35202492211838
2020	48.40342679127726
2021	49.45482866043614