Year	sq. km
1961	6160
1962	6010
1963	6050
1964	5850
1965	6090
1966	5810
1967	5680
1968	5660
1969	5620
1970	5520
1971	5300
1972	5150
1973	4920
1974	4940
1975	4930
1976	4930
1977	4910
1978	4950
1979	4860
1980	4750
1981	4670
1982	4670
1983	4660
1984	4640
1985	4610
1986	4630
1987	4620
1988	4620
1989	4500
1990	4350
1991	4200
1992	4100
1993	3110
1994	3090
1995	3090
1996	3090
1997	2910
1998	2725
1999	2599
2000	2472
2001	2347
2002	2220
2003	2156
2004	2090
2005	2024
2006	1958
2007	1890
2008	1907
2009	1923
2010	1939
2011	1955
2012	1968
2013	1922
2014	1876
2015	1830
2016	1784
2017	1738
2018	1689
2019	1689
2020	1689
2021	1689