Year	sq. km
1992	19600
1993	19675
1994	19750
1995	19825
1996	19900
1997	19975
1998	20050
1999	20125
2000	20200
2001	20350
2002	20500
2003	20650
2004	20800
2005	20950
2006	21100
2007	21250
2008	21400
2009	21550
2010	21700
2011	21734
2012	21768
2013	21802
2014	21836
2015	21870
2016	21900
2017	21960
2018	21980
2019	22000
2020	22010
2021	22026.667