Year	% of land area
1992	35.1098888754992
1993	35.042590577647445
1994	34.97582724011601
1995	34.90815604282319
1996	34.83917294360722
1997	34.769681213443334
1998	34.71326926216865
1999	34.640751637389684
2000	34.54994968303366
2001	34.51217567990155
2002	34.47480982980125
2003	34.433262894067575
2004	34.3949861989576
2005	34.35540789096264
2006	34.31605956421625
2007	34.2788383930389
2008	34.24164671232061
2009	34.20533035671583
2010	34.167655783366676
2011	34.142135321658984
2012	34.11660741850482
2013	34.091378557601395
2014	34.065754198197375
2015	34.040222103453395
2016	34.03387469227055
2017	33.99611571496505
2018	33.97969174339002
2019	33.96144084719234
2020	33.94586749329989
2021	33.92054574833605