Year	% of land area
1961	9.990917347865578
1962	10.407811080835604
1963	10.564032697547685
1964	10.564032697547685
1965	10.894641235240691
1966	10.962761126248864
1967	11.035422343324251
1968	11.126248864668483
1969	11.380563124432335
1970	11.380563124432335
1971	11.598546775658493
1972	11.807447774750226
1973	11.807447774750226
1974	11.807447774750226
1975	11.807447774750226
1976	11.807447774750226
1977	11.834695731153497
1978	11.861943687556767
1979	11.90281562216167
1980	11.807447774750226
1981	11.625794732061761
1982	11.444141689373296
1983	11.262488646684831
1984	10.899182561307901
1985	10.762942779291553
1986	10.535876475930973
1987	10.263396911898274
1988	10.08174386920981
1989	9.900090826521344
1990	9.763851044504996
1991	9.673024523160763
1992	9.673024523160763
1993	10
1994	9.932
1995	9.94
1996	9.927
1997	9.9
1998	9.891
1999	9.881
2000	9.872
2001	9.862
2002	9.853000000000002
2003	10.928
2004	10.95519192972159
2005	11.361866612331019
2006	11.869433877560434
2007	12.438076985439402
2008	12.055981762579854
2009	12.358798292832796
2010	12.905701652331736
2011	13.462285784108783
2012	13.59759388405356
2013	13.70847348861506
2014	13.81964639459169
2015	13.930395921248836
2016	14.040920230215551
2017	14.150157367025143
2018	14.343038477172692
2019	14.347349025735697
2020	14.350090687449853
2021	14.455445133099326