Year	% of land area
1992	39.85446543661778
1993	39.81796548214484
1994	39.78279386255999
1995	39.74598637318365
1996	39.70685900800206
1997	39.6667577387826
1998	39.62497654736161
1999	39.57941628183943
2000	39.559354751583314
2001	39.54233495523407
2002	39.52441565871773
2003	39.50050466508602
2004	39.48255762683951
2005	39.46217969650727
2006	39.43104432016529
2007	39.4147814308712
2008	39.398612308660425
2009	39.38179945083719
2010	39.36475764358807
2011	39.384238603135984
2012	39.403686410505344
2013	39.42257689118934
2014	39.44180599758954
2015	39.46198322887359
2016	39.47928850276638
2017	39.481040667708285
2018	39.4998201303943
2019	39.514367180652954
2020	39.533294345535715
2021	39.54829543364143