Year	% of land area
1990	5.572374075984184
1991	5.5876986173530785
1992	5.603023158721973
1993	5.618347700090866
1994	5.63367224145976
1995	5.648996782828656
1996	5.664321324197549
1997	5.679645865566443
1998	5.694970406935337
1999	5.710294948304232
2000	5.725619489673126
2001	5.8095066185318895
2002	5.893393747390653
2003	5.9772808762494165
2004	6.061168005108181
2005	6.1450551339669435
2006	6.228942262825708
2007	6.312829391684471
2008	6.396716520543236
2009	6.480603649401999
2010	6.5644907782607635
2011	6.5644907782607635
2012	6.5644907782607635
2013	6.5644907782607635
2014	6.5644907782607635
2015	6.5644907782607635
2016	6.57069181463199
2017	6.60128813559322
2018	6.61142064714946
2019	6.621553158705701
2020	6.626730354391371
2021	6.635211093990755