Year	% of land area
1961	9.963142954180741
1962	9.96485188257092
1963	9.965788935550762
1964	9.976538038600353
1965	9.970780061576768
1966	9.956761321923253
1967	9.934939669252614
1968	9.915446203844889
1969	9.889924699227702
1970	9.882800709984844
1971	9.81002648750952
1972	9.836169135154229
1973	9.834797159202877
1974	9.923979206652215
1975	9.859092849953168
1976	9.898083348676018
1977	9.950742845857976
1978	9.973955343224938
1979	9.982440996290753
1980	9.995937273304397
1981	10.056594211165658
1982	10.389651854626727
1983	10.75105048651167
1984	11.177567760008857
1985	11.681872803505803
1986	11.770149094429186
1987	11.846131205886701
1988	11.903956243098582
1989	11.970303988629842
1990	12.030119960651778
1991	11.96550352608209
1992	11.828234784913587
1993	11.719973469651265
1994	11.615141046907839
1995	11.548787297288563
1996	11.580715946600943
1997	11.60941882744605
1998	11.6422288484449
1999	11.717975440133607
2000	11.757735621218593
2001	11.874928565904066
2002	11.93959834401803
2003	11.99316074704209
2004	12.062271366052704
2005	12.081022433307323
2006	12.128592896846692
2007	12.146221518188812
2008	12.184214796557391
2009	12.194278612227487
2010	12.121004417234083
2011	12.046249627720513
2012	11.969300824594969
2013	11.907526076370285
2014	11.848606783886106
2015	11.86199670595532
2016	11.86018506363489
2017	11.835558010100568
2018	11.742944266656608
2019	11.636713230327544
2020	11.633259401711138
2021	11.628587786299066