Year	sq. km
1961	13070
1962	13070
1963	13070
1964	13070
1965	13070
1966	13070
1967	13070
1968	13070
1969	13070
1970	13070
1971	13070
1972	13070
1973	13070
1974	13070
1975	13070
1976	13070
1977	13070
1978	13070
1979	13070
1980	13070
1981	13070
1982	13070
1983	13070
1984	13070
1985	13070
1986	13070
1987	13070
1988	13070
1989	13070
1990	13070
1991	13070
1992	13070
1993	12970
1994	12960
1995	12870
1996	12900
1997	12830
1998	12910
1999	12820
2000	12350
2001	12420
2002	13340
2003	13010
2004	12620
2005	12280
2006	12240
2007	10760
2008	10630
2009	10130
2010	11190
2011	11180
2012	12670
2013	12600
2014	12610
2015	12620
2016	12650
2017	12660
2018	12640
2019	12650
2020	12620
2021	12600