Year	sq. km
1961	13590
1962	13590
1963	13590
1964	13590
1965	13590
1966	13640
1967	13640
1968	13660
1969	13660
1970	13710
1971	13710
1972	13740
1973	13760
1974	13760
1975	13780
1976	13292.417
1977	12804.833
1978	12317.25
1979	11829.667
1980	11342.083
1981	10854.5
1982	10366.917
1983	9879.333
1984	9928
1985	9946.667
1986	9985.333
1987	10004
1988	10022.667
1989	10061.333
1990	10080
1991	10098.667
1992	10117.333
1993	10136
1994	10154.667
1995	10193.333
1996	10222
1997	10240.667
1998	10259.333
1999	10278
2000	10306.667
2001	10345.333
2002	10364
2003	10382.667
2004	10401.333
2005	10420
2006	10420
2007	10420
2008	10420
2009	10420
2010	10420
2011	10420
2012	10420
2013	10420
2014	10420
2015	10420
2016	10420
2017	10420
2018	10420
2019	10420
2020	10420
2021	10430