Year	% of land area
1961	16.611295681063122
1962	16.611295681063122
1963	16.611295681063122
1964	16.611295681063122
1965	16.611295681063122
1966	16.77740863787375
1967	16.77740863787375
1968	16.77740863787375
1969	16.77740863787375
1970	16.943521594684384
1971	16.943521594684384
1972	16.943521594684384
1973	16.943521594684384
1974	17.109634551495017
1975	17.109634551495017
1976	17.109634551495017
1977	17.109634551495017
1978	17.275747508305646
1979	17.275747508305646
1980	17.275747508305646
1981	17.940199335548172
1982	17.940199335548172
1983	17.940199335548172
1984	17.940199335548172
1985	17.774086378737543
1986	17.940199335548172
1987	18.106312292358805
1988	18.272425249169437
1989	18.438538205980066
1990	18.106312292358805
1991	17.60797342192691
1992	17.275747508305646
1993	17.275747508305646
1994	12.264053156146181
1995	13.776196013289036
1996	12.953571428571427
1997	12.713156146179402
1998	12.973006644518273
1999	9.235847176079735
2000	11.829418604651163
2001	11.778887043189368
2002	12.256328903654486
2003	12.04267441860465
2004	12.275382059800664
2005	12.527558139534884
2006	12.581445182724252
2007	12.26393687707641
2008	12.451229235880398
2009	11.096345514950166
2010	7.259136212624585
2011	7.348239202657808
2012	7.943970099667775
2013	10.23406976744186
2014	9.876328903654485
2015	9.518571428571429
2016	9.704019933554816
2017	9.69343853820598
2018	9.018421926910298
2019	8.34340531561462
2020	7.6683720930232555
2021	6.954356846473029