Year	% of land area
1961	6.45
1962	6.45
1963	6.45
1964	6.45
1965	6.45
1966	6.45
1967	6.45
1968	6.45
1969	6.45
1970	6.45
1971	6.45
1972	6.45
1973	6.45
1974	6.45
1975	6.45
1976	6.45
1977	6.45
1978	6.45
1979	6.45
1980	6.45
1981	6.45
1982	6.45
1983	6.45
1984	6.45
1985	6.45
1986	6.45
1987	6.45
1988	6.45
1989	6.45
1990	6.45
1991	6.569999999999999
1992	6.64
1993	6.76
1994	6.88
1995	7.000000000000001
1996	7.12
1997	7.24
1998	7.359999999999999
1999	7.430000000000001
2000	7.55
2001	7.6499999999999995
2002	7.75
2003	7.85
2004	7.95
2005	8.05
2006	8.15
2007	8.25
2008	8.35
2009	8.450000000000001
2010	8.55
2011	8.649999999999999
2012	8.75
2013	8.85
2014	8.95
2015	9.049999999999999
2016	9.15
2017	9.25
2018	9.35
2019	9.45
2020	9.55
2021	9.65