Year	% of land area
1961	13.788714467543487
1962	14.849384811200677
1963	15.379719983029275
1964	15.910055154857869
1965	18.031395842172255
1966	18.56173101400085
1967	18.031395842172255
1968	19.092066185829445
1969	19.62240135765804
1970	19.092066185829445
1971	20.68307170131523
1972	21.21340687314383
1973	21.74374204497242
1974	21.74374204497242
1975	21.21340687314383
1976	21.21340687314383
1977	21.21340687314383
1978	21.74374204497242
1979	21.74374204497242
1980	20.15273652948664
1981	21.21340687314383
1982	22.274077216801018
1983	21.21340687314383
1984	21.74374204497242
1985	21.74374204497242
1986	22.804412388629615
1987	22.804412388629615
1988	22.804412388629615
1989	23.33474756045821
1990	23.865082732286805
1991	24.925753075943994
1992	24.3954179041154
1993	24.3954179041154
1994	22.274077216801018
1995	24.3954179041154
1996	25.45608824777259
1997	25.98642341960119
1998	27.577428935086974
1999	28.638099278744168
2000	29.16843445057276
2001	30.229104794229954
2002	30.229104794229954
2003	31.820110309715737
2004	31.820110309715737
2005	33.94145099703012
2006	35.00212134068732
2007	35.00212134068732
2008	36.5931268561731
2009	37.1234620280017
2010	37.1234620280017
2011	37.1234620280017
2012	37.1234620280017
2013	37.60076368264743
2014	38.19473907509546
2015	38.77810776410692
2016	39.37208315655494
2017	39.9554518455664
2018	40.549427238014424
2019	41.13279592702588
2020	41.72677131947391
2021	42.42681374628766