Year	% of land area
1961	0.25
1962	0.25
1963	0.3
1964	0.35000000000000003
1965	0.375
1966	0.375
1967	0.375
1968	0.375
1969	0.375
1970	0.375
1971	0.375
1972	0.375
1973	0.375
1974	0.35000000000000003
1975	0.25
1976	0.25
1977	0.27499999999999997
1978	0.25
1979	0.35000000000000003
1980	0.35000000000000003
1981	0.35000000000000003
1982	0.35000000000000003
1983	0.42500000000000004
1984	0.375
1985	0.325
1986	0.25
1987	0.25
1988	0.25
1989	0.25
1990	0.25
1991	0.25
1992	0.22499999999999998
1993	0.22499999999999998
1994	0.22499999999999998
1995	0.22499999999999998
1996	0.22499999999999998
1997	0.2
1998	0.2
1999	0.2
2000	0.2
2001	0.2
2002	0.17500000000000002
2003	0.2
2004	0.17500000000000002
2005	0.17500000000000002
2006	0.15
2007	0.17500000000000002
2008	0.125
2009	0.15
2010	0.125
2011	0.1
2012	0.15
2013	0.635
2014	0.690775
2015	0.6812
2016	0.7250000000000001
2017	0.7250000000000001
2018	0.775
2019	0.58365
2020	0.6663
2021	0.675