Year	sq. km
1990	180.7
1991	180.36
1992	180.02
1993	179.68
1994	179.34
1995	179
1996	178.66
1997	178.32
1998	177.98
1999	177.64
2000	177.3
2001	177
2002	176.7
2003	176.4
2004	176.1
2005	175.8
2006	175.5
2007	175.2
2008	174.9
2009	174.6
2010	174.3
2011	174
2012	173.7
2013	173.4
2014	173.1
2015	172.8
2016	172.5
2017	172.2
2018	171.9
2019	171.6
2020	171.3
2021	171