Year	% of land area
1961	56.25
1962	53.125
1963	50
1964	46.875
1965	43.75
1966	43.75
1967	43.75
1968	43.75
1969	43.75
1970	43.75
1971	43.75
1972	43.75
1973	43.75
1974	43.75
1975	40.625
1976	40.625
1977	43.75
1978	43.75
1979	43.75
1980	40.625
1981	40.625
1982	40.625
1983	40.625
1984	40.625
1985	40.625
1986	40.625
1987	40.625
1988	40.625
1989	40.625
1990	40.625
1991	40.625
1992	40.625
1993	40.625
1994	40.625
1995	34.375
1996	34.375
1997	31.25
1998	28.125
1999	28.125
2000	28.125
2001	31.25
2002	31.25
2003	32.5
2004	31.25
2005	29.062500000000004
2006	29.062500000000004
2007	29.062500000000004
2008	29.062500000000004
2009	29.062500000000004
2010	32.28125
2011	32.28125
2012	32.1875
2013	31.96875
2014	31.96875
2015	31.96875
2016	32.4375
2017	32.4375
2018	32.4375
2019	32.4375
2020	28.46875
2021	27.34375