Year	% of land area
1961	3.125
1962	3.125
1963	3.125
1964	3.125
1965	3.125
1966	3.125
1967	3.125
1968	3.125
1969	3.125
1970	3.125
1971	3.125
1972	3.125
1973	3.125
1974	3.125
1975	3.125
1976	3.125
1977	3.125
1978	3.125
1979	3.125
1980	3.125
1981	3.125
1982	3.125
1983	3.125
1984	3.125
1985	3.125
1986	3.125
1987	3.125
1988	3.125
1989	3.125
1990	3.125
1991	3.125
1992	3.125
1993	3.125
1994	3.125
1995	3.125
1996	3.125
1997	3.125
1998	3.125
1999	3.125
2000	3.125
2001	3.125
2002	3.125
2003	3.4375000000000004
2004	3.125
2005	3.4375000000000004
2006	3.4375000000000004
2007	4.0625
2008	4.0625
2009	4.0625
2010	3.90625
2011	3.90625
2012	4.0625
2013	3.9375
2014	3.9375
2015	3.9375
2016	4.09375
2017	4.09375
2018	4.09375
2019	4.09375
2020	4.09375
2021	2.96875