Year	% of land area
1961	45.98010158992758
1962	45.96480371827706
1963	45.99289711426368
1964	45.850497260544515
1965	45.70973097412383
1966	45.674159531860234
1967	45.604465062302005
1968	45.49658034506209
1969	45.672648251904114
1970	45.18145851644517
1971	44.81895351120974
1972	44.77293932545392
1973	44.62298742878949
1974	44.438535499244885
1975	44.255355113478586
1976	44.140057736637786
1977	44.1186788230636
1978	44.110963845627715
1979	44.18538962085267
1980	44.041840994827965
1981	43.96255754468351
1982	43.6540395670309
1983	43.352855374612375
1984	43.47573622026841
1985	43.49346350526912
1986	43.483932701932694
1987	43.618591837036085
1988	43.49079621913903
1989	43.50584181947022
1990	43.334689418163926
1991	43.00198929249725
1992	30.675946223941672
1993	30.652295741121588
1994	30.607607352698963
1995	30.328449429505245
1996	30.246549241193947
1997	30.22009491691086
1998	30.16352300464636
1999	30.118491800340614
2000	30.07844549169594
2001	29.96970956358438
2002	29.83293765839778
2003	29.704667647516075
2004	29.632712920598077
2005	29.586901241958184
2006	29.545127299558654
2007	29.388019292220214
2008	29.374469069223853
2009	29.291963465894078
2010	29.453504089345536
2011	29.36696932394661
2012	29.332688655818913
2013	29.309540607164056
2014	29.253808412286006
2015	29.217746561443963
2016	29.180963443695777
2017	29.166343030695106
2018	29.115268694295196
2019	29.090460217267303
2020	29.024269990332005
2021	29.01049456606385