Year	% of land area
1961	19.389146441232615
1962	19.416416689391873
1963	19.14371420779929
1964	19.170984455958546
1965	19.100081810744477
1966	18.80556313062449
1967	18.64739569130079
1968	18.535587673847832
1969	18.140169075538587
1970	18.260158167439325
1971	17.842923370602673
1972	17.65139116202946
1973	17.5177304964539
1974	17.394980905619203
1975	17.25238744884038
1976	17.115961800818553
1977	17.03056768558952
1978	16.943231441048034
1979	16.85589519650655
1980	16.794976794976797
1981	16.705786026200872
1982	16.641179683233208
1983	16.572910977607865
1984	16.569783383602964
1985	16.500274273176082
1986	16.410748560460654
1987	16.341195831047724
1988	16.250685682940208
1989	16.12177729018102
1990	15.995611629182665
1991	15.863960504662645
1992	15.732309380142622
1993	15.595172792100934
1994	15.42786615469007
1995	15.255074053757541
1996	15.089163237311384
1997	14.916323731138545
1998	14.748971193415638
1999	14.598079561042523
2000	14.425240054869684
2001	14.301783264746229
2002	14.19753086419753
2003	14.101508916323732
2004	14.01920438957476
2005	13.936899862825788
2006	13.8639231824417
2007	13.790946502057613
2008	13.715226337448561
2009	13.647736625514403
2010	13.588477366255145
2011	13.495198902606308
2012	13.456790123456791
2013	13.421124828532236
2014	13.36076817558299
2015	13.294924554183812
2016	13.204389574759945
2017	13.108367626886144
2018	13.020576131687243
2019	12.935528120713306
2020	12.844993141289438
2021	12.781893004115227