Year	% of land area
1961	30.863836017569547
1962	30.863836017569547
1963	30.8696925329429
1964	30.872620790629572
1965	30.872620790629572
1966	30.872620790629572
1967	30.872620790629572
1968	30.872620790629572
1969	30.875549048316252
1970	30.887262079062953
1971	30.887262079062953
1972	30.89311859443631
1973	30.904831625183014
1974	30.916544655929723
1975	30.92825768667643
1976	30.945827232796486
1977	30.937042459736457
1978	30.805270863836014
1979	30.811127379209367
1980	30.819912152269403
1981	30.828696925329428
1982	30.904831625183014
1983	30.916544655929723
1984	30.92825768667643
1985	30.945827232796486
1986	30.937042459736457
1987	30.863836017569547
1988	30.8696925329429
1989	30.875549048316252
1990	30.808199121522694
1991	30.814055636896047
1992	30.819912152269403
1993	30.834553440702784
1994	30.799414348462665
1995	30.805270863836014
1996	30.811127379209367
1997	30.852122986822838
1998	30.85797950219619
1999	30.875549048316252
2000	30.863836017569547
2001	30.863836017569547
2002	30.863836017569547
2003	30.863836017569547
2004	30.878477306002928
2005	30.88433382137628
2006	30.89311859443631
2007	30.89311859443631
2008	30.89311859443631
2009	30.931185944363104
2010	30.9692532942899
2011	31.027818448023424
2012	31.045387994143486
2013	31.118594436310392
2014	31.118594436310392
2015	31.118594436310392
2016	31.118594436310392
2017	31.121522693997072
2018	31.1303074670571
2019	31.136163982430453
2020	31.153733528550514
2021	31.267935578330892