Year	% of land area
1961	3.3173641869294044
1962	3.47102955798608
1963	3.5523818132513783
1964	3.5614209527253005
1965	3.5794992316731444
1966	3.597577510620989
1967	3.6879689053602096
1968	3.651812347464521
1969	3.5885383711470666
1970	3.4800686974600015
1971	3.47102955798608
1972	3.4529512790382357
1973	3.4529512790382357
1974	3.525264394829612
1975	3.4891078369339237
1976	3.4981469764078463
1977	3.3987164421947034
1978	3.272168489559794
1979	3.2269727921901836
1980	3.1636988158727286
1981	3.0913857000813523
1982	3.0009943053421315
1983	2.9738768869203653
1984	2.964837747446443
1985	2.9286811895507547
1986	2.838289794811534
1987	2.765976679020157
1988	2.711741842176625
1989	2.6936635632287804
1990	2.711741842176625
1991	2.6936635632287804
1992	2.5580764711199495
1993	2.2326674500587544
1994	1.9524541263671698
1995	1.8439844526801048
1996	1.7987887553104944
1997	1.7987887553104944
1998	2.5309590526981833
1999	2.539998192172105
2000	2.2778631474283646
2001	2.2145891711109105
2002	2.0955882352941173
2003	1.967454261285281
2004	1.940051489518205
2005	1.7304860088365244
2006	1.6754119488170856
2007	1.7401712549488995
2008	1.69413497836295
2009	1.5198968312453942
2010	1.5106853352984526
2011	1.4738393515106853
2012	1.4646278555637435
2013	1.2435519528371408
2014	1.1698599852616065
2015	1.229734708916728
2016	1.2988209285187913
2017	1.3641304347826086
2018	1.4093588798820929
2019	1.4093588798820929
2020	1.400147383935151
2021	1.3729025423728813