Year	% of land area
1990	27.71390217421505
1991	27.637463018421258
1992	26.587886961670577
1993	26.516753694524972
1994	26.45324528430889
1995	26.382091516199413
1996	26.310937748089945
1997	26.239783971651075
1998	26.168630195212206
1999	26.097476422938033
2000	26.030133180151655
2001	25.95199082563262
2002	25.874414968543512
2003	25.789011998352183
2004	25.713079182208144
2005	25.631996052889384
2006	25.550590027805093
2007	25.472541969302373
2008	25.39440244761276
2009	25.315762212350005
2010	25.237347619893722
2011	25.1466223182053
2012	25.055763258126863
2013	24.96547977101383
2014	24.875514315799958
2015	24.780534116585162
2016	24.69918193880368
2017	24.614102704584777
2018	24.523160002726698
2019	24.432810243319157
2020	24.34265137333687
2021	24.252455409789206