Year	% of land area
1961	35.76758022844804
1962	35.97447322312854
1963	36.19403462266393
1964	36.41825804040553
1965	36.678919058884134
1966	36.93006322947387
1967	37.191241133441316
1968	37.4391087650331
1969	37.734772289057894
1970	38.061080276821926
1971	38.30365030319082
1972	38.66793524325097
1973	39.06417425307282
1974	39.55990557638076
1975	39.90140748112513
1976	39.38482137180197
1977	39.849923806459174
1978	40.269061477589744
1979	40.52424671085041
1980	40.84775039796448
1981	41.21483474948576
1982	41.85921811426162
1983	42.55681335094844
1984	43.22443973674148
1985	44.19318973477488
1986	44.73108969060248
1987	45.30436478582677
1988	45.77588885870471
1989	46.241911178877565
1990	46.69597535161831
1991	46.87556026922749
1992	46.89560606464847
1993	46.90748156563251
1994	47.174488797434925
1995	47.24173342406493
1996	47.291645282757194
1997	48.016111412820045
1998	48.0737902471833
1999	48.30474736536722
2000	48.2932369482955
2001	48.46775755165804
2002	48.600898064112826
2003	47.73394123120903
2004	47.86774430354211
2005	47.937591205872955
2006	48.128266024864466
2007	48.27747759350521
2008	48.38388559251596
2009	48.48772466071825
2010	48.49623744754417
2011	48.53926396383248
2012	48.52457875633371
2013	48.53767790273617
2014	48.50012547514606
2015	48.6069423752937
2016	48.6796722119088
2017	48.87653139986899
2018	48.86492278113158
2019	48.84783622443094
2020	48.83624587321396
2021	48.82538262974743