Year	sq. km
1961	17230
1962	17070
1963	20600
1964	21030
1965	21560
1966	22050
1967	22550
1968	23210
1969	23280
1970	23330
1971	23390
1972	23450
1973	23510
1974	23570
1975	23590
1976	23960
1977	24330
1978	24690
1979	23590
1980	23490
1981	23490
1982	22960
1983	23080
1984	23110
1985	23150
1986	23260
1987	23340
1988	23370
1989	23400
1990	23390
1991	23420
1992	23440
1993	23200
1994	23230
1995	23260
1996	23270
1997	23280
1998	23290
1999	23450
2000	23500
2001	23510
2002	23560
2003	23700
2004	23100
2005	25100
2006	24400
2007	23900
2008	25950
2009	26100
2010	26200
2011	27300
2012	27400
2013	27400
2014	27400
2015	27400
2016	27500
2017	27602
2018	28116
2019	28115.728
2020	28120
2021	28120