Year	% of land area
1992	23.830121903263862
1993	23.94809280377507
1994	23.94809280377507
1995	23.830121903263862
1996	23.94809280377507
1997	23.594180102241445
1998	23.082972866692884
1999	23.12229650019662
2000	21.82461659457334
2001	22.335823830121903
2002	19.622493118364137
2003	18.521431380259536
2004	18.128195045222178
2005	17.616987809673613
2006	17.26307510813999
2007	17.082837891399127
2008	16.805390408244154
2009	16.653449643140362
2010	16.41554321966693
2011	16.41554321966693
2012	16.41554321966693
2013	16.375892149088024
2014	16.33624107850912
2015	16.41554321966693
2016	16.49484536082474
2017	16.534496431403646
2018	16.57414750198255
2019	16.613798572561457
2020	16.49484536082474
2021	16.534496431403646