Year	% of land area
1961	8.060182697474476
1962	8.060182697474476
1963	8.060182697474476
1964	8.060182697474476
1965	8.060182697474476
1966	8.060182697474476
1967	8.060182697474476
1968	8.060182697474476
1969	8.060182697474476
1970	8.060182697474476
1971	8.060182697474476
1972	8.060182697474476
1973	8.060182697474476
1974	8.060182697474476
1975	8.060182697474476
1976	8.060182697474476
1977	8.060182697474476
1978	10.746910263299302
1979	10.746910263299302
1980	10.746910263299302
1981	10.746910263299302
1982	10.746910263299302
1983	10.746910263299302
1984	16.12036539494895
1985	16.12036539494895
1986	16.12036539494895
1987	17.732401934443846
1988	18.26974744760881
1989	18.26974744760881
1990	18.26974744760881
1991	18.807092960773776
1992	18.807092960773776
1993	20.419129500268674
1994	21.493820526598604
1995	22.568511552928534
1996	23.643202579258464
1997	24.717893605588394
1998	24.717893605588394
1999	25.25523911875336
2000	25.792584631918324
2001	26.867275658248253
2002	27.40462117141322
2003	27.941966684578183
2004	28.479312197743152
2005	28.479312197743152
2006	28.479312197743152
2007	28.479312197743152
2008	28.479312197743152
2009	28.479312197743152
2010	28.479312197743152
2011	28.479312197743152
2012	28.479312197743152
2013	28.479312197743152
2014	28.479312197743152
2015	28.479312197743152
2016	28.479312197743152
2017	28.479312197743152
2018	28.479312197743152
2019	28.479312197743152
2020	28.479312197743152
2021	28.479312197743152