Year	% of land area
1990	6.779597287134975
1991	6.797633271251362
1992	6.815669255367747
1993	6.833705239484134
1994	6.85174122360052
1995	6.869777207716907
1996	6.887813191833294
1997	6.905849175949679
1998	6.923885160066065
1999	6.94192114418245
2000	6.959957128298837
2001	6.899365709667219
2002	6.838774291035597
2003	6.778182872403978
2004	6.717591453772358
2005	6.657000035140739
2006	6.59640861650912
2007	6.535817197877498
2008	6.47522577924588
2009	6.414634360614261
2010	6.354042941982641
2011	6.321035246160875
2012	6.288027550339108
2013	6.255019854517342
2014	6.222012158695576
2015	6.189004462873809
2016	6.240942474610816
2017	6.292880486347824
2018	6.3448184980848295
2019	6.3448184980848295
2020	6.3448184980848295
2021	6.3448184980848295