Year	% of land area
1961	25.859987929993967
1962	26.1248575068732
1963	26.393079863206598
1964	27.331858110373496
1965	27.26480252129015
1966	27.258096962381817
1967	27.844833366861128
1968	27.76436665996111
1969	27.670488835244416
1970	27.861597264131966
1971	27.757661101052772
1972	28.263930798632064
1973	28.823391342252624
1974	29.71930648244408
1975	30.828051111781868
1976	32.44457859610289
1977	33.83975584398162
1978	34.00744541704397
1979	34.85930844820069
1980	35.63403427574873
1981	35.784954891504846
1982	36.01972029379213
1983	36.153871952242014
1984	36.28802361069189
1985	36.589864842204115
1986	36.824630244491395
1987	36.958781902941276
1988	37.09293356139115
1989	37.22708521984103
1990	37.36123687829091
1991	37.418251333132105
1992	37.27739209175974
1993	37.10970251869738
1994	36.94201294563504
1995	36.94201294563504
1996	37.24385417714727
1997	38.01522621323406
1998	37.84753664017171
1999	37.67984706710937
2000	37.67649327564812
2001	37.50880370258577
2002	37.34446792098468
2003	37.696616024415604
2004	38.4679880605024
2005	38.082302042459
2006	38.83690512123956
2007	39.541201328101415
2008	40.279035449575744
2009	40.58087668108797
2010	40.58087668108797
2011	41.11748331488748
2012	41.68762786329946
2013	41.81842573028809
2014	41.91568568266425
2015	42.01294563504041
2016	42.11020558741658
2017	42.22423449709897
2018	42.301371700707655
2019	42.378508904316334
2020	42.45564610792501
2021	42.536137102994935