Year	% of land area
1961	23.4052757793765
1962	23.4052757793765
1963	23.4052757793765
1964	23.11750599520384
1965	22.829736211031175
1966	22.54196642685851
1967	22.25419664268585
1968	21.966426858513188
1969	21.822541966426858
1970	21.58273381294964
1971	23.4052757793765
1972	23.4052757793765
1973	23.4052757793765
1974	23.4052757793765
1975	23.4052757793765
1976	22.924710424710426
1977	22.924710424710426
1978	24.855212355212355
1979	27.027027027027028
1980	26.930501930501933
1981	24.903474903474905
1982	23.11776061776062
1983	22.683397683397683
1984	23.166023166023166
1985	24.13127413127413
1986	25.096525096525095
1987	25.096525096525095
1988	26.061776061776058
1989	26.061776061776058
1990	26.54440154440155
1991	27.268339768339768
1992	28.37837837837838
1993	28.28185328185328
1994	28.185328185328185
1995	28.08880308880309
1996	27.268339768339768
1997	27.268339768339768
1998	28.957528957528954
1999	30.453667953667953
2000	30.265444015444015
2001	30.07722007722008
2002	29.888996138996138
2003	29.700772200772203
2004	29.51254826254826
2005	29.324324324324323
2006	29.150579150579148
2007	30.429536679536678
2008	30.83011583011583
2009	31.230694980694977
2010	31.63127413127413
2011	32.03185328185329
2012	32.432432432432435
2013	32.83301158301158
2014	33.23359073359073
2015	33.634169884169886
2016	34.034749034749034
2017	34.43532818532818
2018	34.7972972972973
2019	34.7972972972973
2020	34.7972972972973
2021	34.7972972972973