Year	% of land area
1990	23.5468755373663
1991	23.432905733053616
1992	23.31893592874093
1993	23.204966124428243
1994	23.090996320115558
1995	22.97702651580287
1996	22.86305671149018
1997	22.749086907177496
1998	22.63511710286481
1999	22.52114729855212
2000	22.407177494239434
2001	22.326582866182893
2002	22.245988238126355
2003	22.165393610069817
2004	22.084798982013275
2005	22.004204353956737
2006	21.923609725900196
2007	21.843015097843654
2008	21.762420469787116
2009	21.68182584173058
2010	21.601231213674037
2011	21.569044079100024
2012	21.546324736376217
2013	21.523420419388106
2014	21.50070127191475
2015	21.47798212444139
2016	21.45527672739773
2017	21.43255414231695
2018	21.40983155723616
2019	21.38712616019251
2020	21.364403575111723
2021	21.34169250601581