Year	sq. km
1961	14420
1962	14620
1963	14820
1964	15020
1965	15220
1966	15520
1967	15920
1968	16220
1969	17070
1970	17270
1971	17770
1972	18070
1973	18270
1974	18570
1975	18970
1976	19270
1977	19570
1978	19770
1979	19970
1980	20270
1981	20570
1982	20900
1983	21000
1984	21100
1985	21300
1986	21900
1987	22000
1988	22100
1989	22200
1990	22700
1991	22800
1992	22950
1993	23200
1994	24000
1995	25200
1996	27100
1997	28900
1998	30500
1999	31100
2000	31950
2001	32650
2002	33650
2003	34670
2004	34670
2005	34840
2006	33400
2007	33500
2008	35500
2009	36500
2010	36500
2011	36500
2012	37500
2013	39500
2014	39500
2015	39500
2016	39500
2017	39500
2018	39500
2019	39500
2020	39500
2021	39500