Year	% of land area
1961	56.25
1962	56.25
1963	56.25
1964	56.25
1965	56.25
1966	56.25
1967	56.25
1968	56.25
1969	56.25
1970	56.25
1971	56.25
1972	56.25
1973	56.25
1974	56.25
1975	56.25
1976	56.25
1977	56.25
1978	56.25
1979	56.25
1980	56.25
1981	56.25
1982	56.25
1983	56.25
1984	56.25
1985	56.25
1986	50
1987	50
1988	50
1989	50
1990	43.75
1991	43.75
1992	43.75
1993	43.75
1994	43.75
1995	43.75
1996	43.75
1997	43.75
1998	43.75
1999	43.75
2000	43.75
2001	43.125
2002	42.3125
2003	41.5
2004	40.6875
2005	39.875
2006	39.0625
2007	38.25
2008	37.4375
2009	36.625
2010	35.8125
2011	35
2012	34.1875
2013	33.375
2014	32.75
2015	32.625
2016	32.5
2017	32.375
2018	32.375
2019	32.3125
2020	32.3125
2021	32.3125