Year	% of land area
1961	14.021254713747
1962	13.689864015541081
1963	13.358473317335163
1964	13.032796251856931
1965	12.70140555365101
1966	12.37572848817278
1967	11.958633299051536
1968	11.541538109930293
1969	11.118729288081362
1970	10.30739344074963
1971	10.078848131642099
1972	9.844589189806879
1973	9.621757513427037
1974	9.393212204319507
1975	9.164666895211976
1976	8.936121586104445
1977	8.707576276996914
1978	8.479030967889384
1979	8.244772026054164
1980	8.016226716946635
1981	7.924808593303623
1982	7.8276768369329215
1983	7.736258713289909
1984	7.644840589646898
1985	7.553422466003886
1986	7.47343160781625
1987	7.376299851445549
1988	7.284881727802536
1989	7.182036338704148
1990	7.090618215061135
1991	7.164895440521084
1992	7.23917266598103
1993	7.313449891440977
1994	7.387727116900926
1995	7.462004342360872
1996	7.536281567820821
1997	7.616272426008456
1998	7.6962632841960925
1999	7.776254142383728
2000	7.844817735115988
2001	7.86767226602674
2002	7.890526796937493
2003	7.913381327848246
2004	7.936235858758998
2005	7.953376756942064
2006	7.9762312878528165
2007	8.433321906067878
2008	10.43309336075877
2009	12.541423837275739
2010	11.615815335390241
2011	13.438464175522796
2012	12.34144669180665
2013	13.185350245686205
2014	13.918980687921382
2015	13.876128442463717
2016	12.720260541652383
2017	12.4780025139984
2018	12.294594903439608
2019	11.931779225231402
2020	11.566678093932122
2021	11.602131185007428