Year	sq. km
1961	12520
1962	12520
1963	12519
1964	12438
1965	12347
1966	12235
1967	12134
1968	12023
1969	11952
1970	11881
1971	12260
1972	12238
1973	12257
1974	12306
1975	12355
1976	12224
1977	12263
1978	12622
1979	13070
1980	13119
1981	12668
1982	12327
1983	12236
1984	12285
1985	12433
1986	12582
1987	12531
1988	12680
1989	12629
1990	12708
1991	12837
1992	13015
1993	12964
1994	12943
1995	12902
1996	12461
1997	12410
1998	12698
1999	12957
2000	12867
2001	12777
2002	12637
2003	12547
2004	12807
2005	12186
2006	12169
2007	12413
2008	12375
2009	12337
2010	12299
2011	12260
2012	12222
2013	12184
2014	12142
2015	12230
2016	12141
2017	12052
2018	11957
2019	11957
2020	11957
2021	11957