Year	% of land area
1961	29.383886255924168
1962	28.613744075829384
1963	28.110189573459714
1964	27.75473933649289
1965	27.488151658767773
1966	26.860189573459714
1967	26.116706161137444
1968	25.82642180094787
1969	25.266587677725116
1970	24.650473933649288
1971	24.16765402843602
1972	23.995853080568722
1973	23.797393364928908
1974	23.886255924170616
1975	23.97808056872038
1976	24.10841232227488
1977	24.71563981042654
1978	24.51718009478673
1979	24.617890995260662
1980	25.0414691943128
1981	25.053317535545023
1982	25.24585308056872
1983	24.700829383886255
1984	24.93483412322275
1985	25.512440758293835
1986	26.007109004739338
1987	26.466232227488153
1988	26.77132701421801
1989	26.851303317535546
1990	27.381516587677723
1991	26.43068720379147
1992	26.66469194312796
1993	26.726895734597157
1994	26.756516587677726
1995	27.22156398104265
1996	27.46149289099526
1997	28.76777251184834
1998	27.544431279620852
1999	29.958530805687207
2000	30.29324644549763
2001	29.881516587677726
2002	30.07109004739337
2003	32.319312796208536
2004	33.39751184834123
2005	32.90876777251185
2006	31.688388625592417
2007	31.39218009478673
2008	31.593601895734597
2009	31.268900088941592
2010	30.3172250222354
2011	29.833926453143533
2012	29.98220640569395
2013	30.822202433956665
2014	31.018106262986052
2015	30.94743094743095
2016	30.531630531630533
2017	30.7989307989308
2018	30.323730323730324
2019	30.02970002970003
2020	29.84348084348084
2021	29.789129789129788