Year	% of land area
1990	0.699908470278032
1991	0.6962136925105176
1992	0.692518914743003
1993	0.6888241369754885
1994	0.685129359207974
1995	0.6814345814404595
1996	0.677739803672945
1997	0.6740450259054305
1998	0.670350248137916
1999	0.6666554703704015
2000	0.6629606926028869
2001	0.6771939842300168
2002	0.6914272758571465
2003	0.7056605674842762
2004	0.719893859111406
2005	0.7341271507385356
2006	0.7483604423656655
2007	0.7625937339927952
2008	0.7768270256199249
2009	0.7910603172470547
2010	0.8052936088741844
2011	0.8084845533097651
2012	0.8116754977453459
2013	0.8148664421809266
2014	0.8180573866165072
2015	0.8212479862419969
2016	0.8212479862419969
2017	0.8157897941043968
2018	0.8103316019667967
2019	0.8141103503697505
2020	0.818308959706366
2021	0.8222276477585093