Year	% of land area
1990	12.849614916903121
1991	12.72800972841508
1992	12.606404539927038
1993	12.484799351438996
1994	12.363194162950952
1995	12.24158897446291
1996	12.119983785974869
1997	11.998378597486827
1998	11.876773408998783
1999	11.755168220510742
2000	11.6335630320227
2001	11.544385893798136
2002	11.455208755573572
2003	11.366031617349007
2004	11.276854479124443
2005	11.187677340899878
2006	11.098500202675314
2007	11.00932306445075
2008	10.920145926226185
2009	10.830968788001622
2010	10.741791649777058
2011	10.782326712606405
2012	10.822861775435753
2013	10.8633968382651
2014	10.903931901094447
2015	10.944466963923794
2016	11.025537089582489
2017	11.066072152411836
2018	11.106607215241183
2019	11.14714227807053
2020	11.187677340899878
2021	11.228212403729227