Year	% of land area
1990	63.57807010507741
1991	63.45340739552419
1992	63.32874468597096
1993	63.20408197641775
1994	63.07941926686452
1995	62.9547565573113
1996	62.830093847758086
1997	62.70543113820486
1998	62.58076842865164
1999	62.45610571909842
2000	62.3314430095452
2001	61.886218817678674
2002	61.44099462581214
2003	60.995770433945616
2004	60.55054624207909
2005	60.105322050212564
2006	59.66009785834603
2007	59.214873666479505
2008	58.769649474612976
2009	58.32442528274645
2010	57.87920109087993
2011	57.4339760968958
2012	56.988751102911685
2013	56.543526108927566
2014	56.09830111494345
2015	55.653076120959334
2016	55.20784471003449
2017	54.762629341461455
2018	54.317405951712516
2019	53.872174540787675
2020	53.42695115103875
2021	52.98172238710194