Year	sq. km
1961	15500
1962	15500
1963	15000
1964	14500
1965	14500
1966	14600
1967	14600
1968	14700
1969	14720
1970	14770
1971	14820
1972	15120
1973	15320
1974	15550
1975	15680
1976	15800
1977	15900
1978	15980
1979	16050
1980	16060
1981	16090
1982	16170
1983	16200
1984	16300
1985	16350
1986	16380
1987	16400
1988	16500
1989	16520
1990	16600
1991	16620
1992	16640
1993	16650
1994	16900
1995	17000
1996	17000
1997	17560
1998	17650
1999	17730
2000	18060
2001	18410
2002	18760
2003	19110
2004	19460
2005	19850
2006	20250
2007	20630
2008	21040
2009	21680
2010	22200
2011	22765
2012	23072.5
2013	23350
2014	23350
2015	23350
2016	23350
2017	22589
2018	21828
2019	21067
2020	20310
2021	20310