Year	% of land area
1961	6.897817098484316
1962	6.9465590106172606
1963	6.9953009227502045
1964	7.044042834883148
1965	7.092784747016092
1966	7.105053878216603
1967	7.089996308106884
1968	7.074938737997165
1969	7.059881167887445
1970	7.044823597777726
1971	7.029431414998902
1972	7.032442929020845
1973	7.03545444304279
1974	7.038465957064734
1975	7.041477471086677
1976	7.044599407289426
1977	7.0028854765832484
1978	6.961058892945138
1979	6.919232309307029
1980	6.877405725668918
1981	6.83613682981265
1982	6.827436900415923
1983	6.818736971019197
1984	6.81003704162247
1985	6.801337112225743
1986	6.7925135992165595
1987	6.806579377375053
1988	6.820633109477457
1989	6.834686841579862
1990	6.848740573682267
1991	6.863267938864034
1992	6.8556559021771015
1993	6.848071348344058
1994	6.840486794511014
1995	6.83290224067797
1996	6.825206149288558
1997	6.827771513085028
1998	6.830448414437868
1999	6.833125315790707
2000	6.835802217143545
2001	6.838162441066344
2002	6.925478412463653
2003	6.90930546679025
2004	6.893132521116847
2005	6.876959575443445
2006	6.757391315016637
2007	6.6931456825485
2008	6.628900050080362
2009	6.564654417612226
2010	6.5004087851440895
2011	6.435683541183569
2012	6.443636168952629
2013	6.4515553354547786
2014	6.459474501956926
2015	6.467505206015443
2016	6.4747551471793825
2017	6.454410696897805
2018	6.45681990811536
2019	6.434356244262787
2020	6.370735222110313
2021	6.484576786100334