Year	% of land area
1961	6.158792082069065
1962	6.158792082069065
1963	6.176853055916775
1964	6.176853055916775
1965	6.194914029764485
1966	6.194914029764485
1967	6.212975003612195
1968	6.194914029764485
1969	6.212975003612195
1970	6.2310359774599045
1971	6.249096951307615
1972	6.267157925155324
1973	6.285218899003034
1974	6.33217743100708
1975	6.212975003612195
1976	6.068487212830516
1977	5.9601213697442565
1978	5.8156335789625775
1979	5.707267735876318
1980	5.570004334633723
1981	5.779511631267158
1982	5.606126282329143
1983	5.635023840485479
1984	5.689206762028609
1985	5.743389683571738
1986	5.797572605114868
1987	5.83730674757983
1988	5.869816500505707
1989	5.718104320184944
1990	5.793960410345326
1991	5.938448201127005
1992	5.898714058662043
1993	5.667533593411356
1994	5.855367721427539
1995	5.685594567259066
1996	5.804796994653952
1997	5.812021384193035
1998	6.450314060235142
1999	6.482525366403608
2000	6.506683846029956
2001	6.039619906587212
2002	5.475922048639072
2003	5.230310839104526
2004	5.141729747141246
2005	5.218231599291352
2006	4.964567563214688
2007	4.811563858914479
2008	4.9766468030278626
2009	4.829280077307135
2010	4.776936704783379
2011	4.653325817361894
2012	4.62191979384764
2013	4.807537445643421
2014	3.9056208729263973
2015	4.3002093734900955
2016	3.929779352552746
2017	4.15928490900306
2018	3.897568046384281
2019	3.982122725076502
2020	4.17941697535835
2021	4.123047189563537