Year	% of land area
1961	64.66702834667028
1962	64.62537977430556
1963	64.54041150700539
1964	64.59195160655915
1965	64.40294053819444
1966	64.44179201649328
1967	64.33822532078236
1968	64.47338080705323
1969	64.34045439131908
1970	64.23688351147523
1971	64.16857697055192
1972	63.99902337126812
1973	63.815905484041615
1974	63.76029190347653
1975	63.60972830731251
1976	63.901737632424954
1977	63.826266243455144
1978	63.73180689879685
1979	63.582842724978974
1980	63.45754710582362
1981	63.26713332248087
1982	63.24086006918537
1983	63.228152047100956
1984	63.29462517296579
1985	63.27427625688472
1986	63.22543885829015
1987	63.2702064736685
1988	63.20187755212785
1989	62.78289455810036
1990	62.75300893851713
1991	62.71239388794566
1992	57.25211490031105
1993	56.55061690183419
1994	56.23855776479244
1995	55.73911729278263
1996	55.269856581427526
1997	55.22530014832083
1998	54.758842996596464
1999	54.705860527747035
2000	53.4901884125256
2001	52.07114407734515
2002	50.43443345820127
2003	49.595843971284104
2004	48.84685687254128
2005	48.88277300984935
2006	48.731612965210445
2007	47.769314373615934
2008	47.99490954276715
2009	47.9163379859727
2010	47.05221206814478
2011	47.21420491953969
2012	46.880341419721795
2013	46.95652213255827
2014	46.862198091769066
2015	46.95507180271642
2016	46.68313702439355
2017	46.63365789216741
2018	46.72113212280084
2019	47.160790806891164
2020	46.30281025081038
2021	46.18865433788542