Year	% of land area
1990	27.778504469151947
1991	27.763008803277263
1992	27.760829774252592
1993	27.758650745227925
1994	27.750424818090714
1995	27.750664516972417
1996	27.744858835831298
1997	27.741471703045356
1998	27.73204407857485
1999	27.728658536585364
2000	27.713203604544862
2001	27.77806799878107
2002	27.823552442684996
2003	27.878669275929553
2004	27.937391304347827
2005	28.00460909644317
2006	28.069397338899034
2007	28.14519987820262
2008	28.20878642888212
2009	28.25393375641137
2010	28.3199304499022
2011	28.640535256549505
2012	28.994800452134594
2013	29.329113593879057
2014	29.658240611961055
2015	29.99374130737135
2016	30.115829276773297
2017	30.115829276773297
2018	30.115829276773297
2019	30.115829276773297
2020	30.115829276773297
2021	30.115829276773297