Year	% of land area
1961	19.76580018270908
1962	19.76580018270908
1963	19.76580018270908
1964	19.76580018270908
1965	19.76580018270908
1966	19.76580018270908
1967	19.76580018270908
1968	19.76580018270908
1969	19.76580018270908
1970	19.76580018270908
1971	19.76580018270908
1972	19.76580018270908
1973	20.181048085707168
1974	20.181048085707168
1975	20.181048085707168
1976	20.181048085707168
1977	20.181048085707168
1978	20.181048085707168
1979	20.181048085707168
1980	20.88696952080392
1981	20.88696952080392
1982	20.88696952080392
1983	20.88696952080392
1984	20.88696952080392
1985	20.88696952080392
1986	20.88696952080392
1987	20.88696952080392
1988	20.88696952080392
1989	20.88696952080392
1990	20.911884394983804
1991	21.011543891703347
1992	21.011543891703347
1993	21.177643052902585
1994	22.00813885889876
1995	22.00813885889876
1996	21.177643052902585
1997	21.177643052902585
1998	21.177643052902585
1999	21.177643052902585
2000	21.177643052902585
2001	21.177643052902585
2002	21.177643052902585
2003	21.177643052902585
2004	21.177643052902585
2005	21.592890955900675
2006	21.592890955900675
2007	21.592890955900675
2008	22.00813885889876
2009	22.174238020098
2010	22.257287600697616
2011	21.842039697699526
2012	21.842039697699526
2013	21.842039697699526
2014	21.842039697699526
2015	21.842039697699526
2016	21.75899011709991
2017	21.592890955900675
2018	21.592890955900675
2019	21.551366165600864
2020	21.551366165600864
2021	21.551366165600864