Year	% of land area
1961	11.11111111111111
1962	11.11111111111111
1963	12.962962962962962
1964	12.962962962962962
1965	12.962962962962962
1966	12.962962962962962
1967	12.962962962962962
1968	12.962962962962962
1969	12.962962962962962
1970	12.962962962962962
1971	12.962962962962962
1972	12.962962962962962
1973	12.962962962962962
1974	12.962962962962962
1975	12.962962962962962
1976	12.962962962962962
1977	12.962962962962962
1978	12.962962962962962
1979	14.814814814814813
1980	14.814814814814813
1981	18.51851851851852
1982	18.51851851851852
1983	18.51851851851852
1984	18.51851851851852
1985	18.51851851851852
1986	18.51851851851852
1987	18.51851851851852
1988	18.51851851851852
1989	18.51851851851852
1990	18.51851851851852
1991	18.51851851851852
1992	18.51851851851852
1993	18.51851851851852
1994	18.51851851851852
1995	18.51851851851852
1996	18.51851851851852
1997	18.51851851851852
1998	18.51851851851852
1999	18.51851851851852
2000	18.51851851851852
2001	18.51851851851852
2002	18.51851851851852
2003	18.51851851851852
2004	18.51851851851852
2005	18.51851851851852
2006	18.51851851851852
2007	18.51851851851852
2008	18.51851851851852
2009	16.666666666666664
2010	16.666666666666664
2011	16.666666666666664
2012	16.666666666666664
2013	16.666666666666664
2014	16.666666666666664
2015	14.814814814814813
2016	14.814814814814813
2017	14.814814814814813
2018	12.962962962962962
2019	12.962962962962962
2020	12.962962962962962
2021	12.962962962962962