Year	% of land area
1961	43.08531265147843
1962	42.78962675714978
1963	42.29035385361124
1964	42.129180804653416
1965	41.98012603005332
1966	41.27484246243335
1967	40.88342220067862
1968	40.70891904992729
1969	40.6095492001939
1970	40.424139602520604
1971	40.243577314590404
1972	40.07634512845371
1973	39.04750363548231
1974	38.86694134755211
1975	38.65123606398449
1976	38.5785264178381
1977	38.50702859912749
1978	38.545807077072226
1979	38.0865244789142
1980	38.06349975763451
1981	38.23800290838585
1982	38.08410082404266
1983	36.66868637905962
1984	36.757149781871064
1985	36.80925836160931
1986	36.67959282598158
1987	36.694134755210854
1988	36.94013572467281
1989	36.96800775569559
1990	36.64444983034416
1991	36.80198739699467
1992	36.512360639844886
1993	36.34270479883664
1994	36.28332525448376
1995	36.12578768783325
1996	36.031265147842944
1997	35.925836160930686
1998	35.86888027144934
1999	35.811924381968005
2000	35.63015026660204
2001	35.338099854580705
2002	35.16965584100824
2003	34.964008725157534
2004	34.74793989335919
2005	34.61948618516723
2006	34.455889481337856
2007	34.2959282598158
2008	34.04507998061076
2009	33.87057682985943
2010	33.67910809500727
2011	33.413717886572954
2012	33.145904023267086
2013	32.91808046534174
2014	32.891420261754725
2015	32.942922927775086
2016	32.35785264178381
2017	32.16941347552108
2018	32.147721764420744
2019	32.12809015996122
2020	31.539813378574888
2021	31.476725642268537