Year	sq. km
1990	23503.3
1991	23319.39
1992	23135.48
1993	22951.57
1994	22767.66
1995	22583.75
1996	22399.84
1997	22215.93
1998	22032.02
1999	21848.11
2000	21664.2
2001	21601.4
2002	21538.6
2003	21475.8
2004	21413
2005	21350.2
2006	21287.4
2007	21224.6
2008	21161.8
2009	21099
2010	21036.2
2011	21086.6
2012	21137
2013	21187.4
2014	21237.8
2015	21288.2
2016	21256.6
2017	21225
2018	21193.4
2019	21161.8
2020	21130.2
2021	21098.6