Year	% of land area
1961	15.037474087067453
1962	15.069366927124861
1963	17.269972891085953
1964	17.269972891085953
1965	17.269972891085953
1966	17.269972891085953
1967	17.269972891085953
1968	17.285919311114657
1969	17.30186573114336
1970	17.285919311114657
1971	17.285919311114657
1972	17.285919311114657
1973	17.285919311114657
1974	17.285919311114657
1975	17.062669430712806
1976	16.85536597033966
1977	16.648062509966515
1978	16.424812629564663
1979	16.265348429277626
1980	16.10588422899059
1981	16.10588422899059
1982	15.946420028703557
1983	15.946420028703557
1984	15.946420028703557
1985	15.946420028703557
1986	15.946420028703557
1987	15.946420028703557
1988	15.946420028703557
1989	15.946420028703557
1990	15.946420028703557
1991	15.946420028703557
1992	15.946420028703557
1993	15.946420028703557
1994	15.946420028703557
1995	15.946420028703557
1996	15.946420028703557
1997	15.946420028703557
1998	15.946420028703557
1999	15.946420028703557
2000	15.866687928560038
2001	15.866687928560038
2002	15.627491628129487
2003	15.627491628129487
2004	15.468027427842449
2005	15.468027427842449
2006	15.14909902726838
2007	15.14909902726838
2008	15.228831127411896
2009	15.468027427842449
2010	15.627491628129487
2011	15.786955828416522
2012	15.946420028703557
2013	15.946420028703557
2014	15.946420028703557
2015	16.15691596788005
2016	16.15691596788005
2017	16.15691596788005
2018	16.164489848700374
2019	16.164367042989298
2020	16.16553507921112
2021	16.16553507921112