Year	% of land area
1992	38.97983457679173
1993	38.994912865016275
1994	39.01200543502767
1995	39.02577101053429
1996	39.03509767918845
1997	39.04247126630708
1998	39.046676757959844
1999	39.04329720470735
2000	39.04610170634713
2001	39.08394068456214
2002	39.12245317704332
2003	39.158620265895834
2004	39.19436898337681
2005	39.230368554884386
2006	39.24592565726848
2007	39.28417998567818
2008	39.323788645386166
2009	39.361981881241825
2010	39.40011209426619
2011	39.41071089414147
2012	39.42119884549758
2013	39.43163574408369
2014	39.444105366302956
2015	39.44608509294426
2016	39.4632904974101
2017	39.48242335664869
2018	39.494572018902815
2019	39.50694838198297
2020	39.52502220700369
2021	39.53721158852391