Year	% of land area
1990	62.45222986862097
1991	62.26498346590401
1992	62.07773706318706
1993	61.89049066047011
1994	61.70324425775314
1995	61.5159978550362
1996	61.32875145231925
1997	61.14150504960229
1998	60.95425864688534
1999	60.767012244168384
2000	60.579765841451426
2001	60.39851640003574
2002	60.21726695862007
2003	60.0360175172044
2004	59.85476807578872
2005	59.673518634373046
2006	59.49226919295736
2007	59.31101975154169
2008	59.12977031012602
2009	58.94852086871034
2010	58.767271427294666
2011	58.56771829475378
2012	58.36816516221288
2013	58.168612029672
2014	57.969058897131106
2015	57.76950576459022
2016	57.58378764858343
2017	57.39663955670748
2018	57.20940209133971
2019	57.02216462597194
2020	56.83492716060417
2021	56.647689695236394