Year	% of land area
1961	16.417910447761194
1962	14.925373134328357
1963	13.432835820895523
1964	13.432835820895523
1965	13.432835820895523
1966	13.432835820895523
1967	13.432835820895523
1968	13.432835820895523
1969	13.432835820895523
1970	11.940298507462686
1971	11.940298507462686
1972	11.940298507462686
1973	11.940298507462686
1974	10.44776119402985
1975	8.955223880597014
1976	8.955223880597014
1977	8.955223880597014
1978	8.955223880597014
1979	8.955223880597014
1980	8.955223880597014
1981	7.462686567164178
1982	5.970149253731343
1983	5.970149253731343
1984	5.970149253731343
1985	4.477611940298507
1986	2.9850746268656714
1987	1.4925373134328357
1988	1.4925373134328357
1989	1.4925373134328357
1990	1.4925373134328357
1991	0.2985074626865672
1992	0.2985074626865672
1993	0.2985074626865672
1994	0.2985074626865672
1995	0.2985074626865672
1996	0.2985074626865672
1997	0.2985074626865672
1998	0.2985074626865672
1999	0.2985074626865672
2000	0.2985074626865672
2001	0.2985074626865672
2002	0.2962962962962963
2003	0.2911208151382824
2004	0.14513788098693758
2005	0.14513788098693758
2006	0.1440922190201729
2007	0.14388489208633093
2008	0.14285714285714285
2009	0.14285714285714285
2010	0.14245014245014245
2011	0.14204545454545456
2012	0.141643059490085
2013	0.14144271570014144
2014	0.14104372355430184
2015	0.14104372355430184
2016	0.14104372355430184
2017	0.1404494382022472
2018	0.1400560224089636
2019	0.13966480446927373
2020	0.1392757660167131
2021	0.1392757660167131