Year	% of land area
1990	32.36616733022083
1991	32.38163434823705
1992	32.39710136625325
1993	32.413496791934
1994	32.429893156884646
1995	32.4462904611859
1996	32.4626887049185
1997	32.48187938690732
1998	32.500143258266
1999	32.51934208264084
2000	32.53761283851554
2001	32.55803955288048
2002	32.577538267499854
2003	32.59797597545942
2004	32.617484301975516
2005	32.63418970065374
2006	32.65370497820601
2007	32.67416181489661
2008	32.693686716576316
2009	32.71133931900978
2010	32.73087184783544
2011	32.73754877209089
2012	32.74516554771332
2013	32.71898647099289
2014	32.722843221553454
2015	32.73232815456057
2016	32.68548202427296
2017	32.684546469359134
2018	32.68361096800046
2019	32.68267552019233
2020	32.68267552019233
2021	32.68267552019233