Year	% of land area
1992	32.5110191391759
1993	32.45485213706991
1994	32.3971532541665
1995	32.33725783777177
1996	32.276722386493844
1997	32.1988190609858
1998	32.14466567870853
1999	32.08235439643639
2000	32.00484632543645
2001	31.96488769275932
2002	31.925177733102558
2003	31.883171370534548
2004	31.80694126089069
2005	31.766064919372432
2006	31.727344667129522
2007	31.687577330296048
2008	31.651626731880214
2009	31.612178526720328
2010	31.571771763963596
2011	31.536963472968605
2012	31.472313842138888
2013	31.43820022402002
2014	31.403806923407757
2015	31.368386454776104
2016	31.34091596008531
2017	31.289997007738908
2018	31.252635742152798
2019	31.213754551826614
2020	31.176904586713945
2021	31.17704902276405