Year	% of land area
1992	33.7471679333121
1993	33.660640382621246
1994	33.5769214450017
1995	33.49011907028443
1996	33.40238371021615
1997	33.31428723166089
1998	33.23546655296187
1999	33.14522043901048
2000	33.03825706992466
2001	32.97685378376934
2002	32.91572001580701
2003	32.85170775493047
2004	32.73972790233053
2005	32.67713690986145
2006	32.61638266117793
2007	32.55541205889758
2008	32.49463325740782
2009	32.434378178760575
2010	32.37297253925865
2011	32.313561859985775
2012	32.212662304306875
2013	32.15364865974892
2014	32.09472731815677
2015	32.034110492583935
2016	31.98909392007852
2017	31.92190240131654
2018	31.870535187874445
2019	31.81673067227522
2020	31.765254441348446
2021	31.706720749965307