Year	% of land area
1990	33.179291726218835
1991	32.970550350254975
1992	32.76180897429111
1993	32.553067598327246
1994	32.344326222363385
1995	32.13558484639952
1996	31.926843470435657
1997	31.718102094471796
1998	31.509360718507935
1999	31.300619342544067
2000	31.091877966580206
2001	30.883136590616346
2002	30.674395214652478
2003	30.465653838688617
2004	30.256912462724756
2005	30.048171086760888
2006	29.839429710797027
2007	29.630688334833167
2008	29.421946958869306
2009	29.213205582905438
2010	29.004464206941577
2011	28.795722830977716
2012	28.58698145501385
2013	28.378240079049988
2014	28.169498703086127
2015	27.960757327122266
2016	27.7520159511584
2017	27.543274575194538
2018	27.334533199230677
2019	27.12579182326681
2020	26.917050447302948
2021	26.708309071339087