Year	sq. km
1961	22340
1962	22370
1963	22400
1964	22430
1965	22180
1966	22320
1967	22320
1968	22340
1969	22370
1970	22300
1971	22400
1972	22410
1973	22550
1974	22569
1975	22560
1976	22092.417
1977	21644.833
1978	21227.25
1979	20681.667
1980	20187.083
1981	19692.5
1982	19036.917
1983	18321.333
1984	18383
1985	18434.667
1986	18517.333
1987	18640.6
1988	18685.667
1989	18770.733
1990	18884.8
1991	18968.867000000002
1992	19042.933
1993	19398
1994	19351.067
1995	19301.133
1996	19290.2
1997	19201.267
1998	19101.333
1999	19155.4
2000	19153.667
2001	19117.333
2002	18966
2003	19032.667
2004	18927.632999999998
2005	18777
2006	18769.1
2007	18710.2
2008	18568.4
2009	18688.4
2010	18462.4
2011	18474.4
2012	18399.4
2013	18484.4
2014	18520.4
2015	18589.4
2016	18579.4
2017	18569.4
2018	18569.4
2019	18589.4
2020	18609.4
2021	18619.4