Year	% of land area
1961	81.29829143541191
1962	81.45608880182827
1963	81.84242028512352
1964	80.8248993361628
1965	77.80498422026336
1966	74.16476221569268
1967	74.16476221569268
1968	73.02753291979542
1969	73.1581238437262
1970	73.23430188268581
1971	73.2288605941887
1972	77.05408640766134
1973	78.77897486124714
1974	78.99118511263468
1975	76.76025682881706
1976	77.33703340951136
1977	76.39569049951028
1978	76.22701055609969
1979	75.960387419741
1980	76.51539884644684
1981	76.80378713679399
1982	76.79290455979975
1983	76.12906736315159
1984	76.0311241702035
1985	75.91141582326695
1986	75.74273587985635
1987	75.67199912939384
1988	74.72521493089563
1989	73.41386440309066
1990	73.430188268582
1991	73.52269017303298
1992	74.0722603112417
1993	74.23005767765807
1994	75.01360322124279
1995	75.02992708673413
1996	75.03536837523126
1997	75.11154641419088
1998	74.83948198933507
1999	74.91021873979759
2000	74.60550658395908
2001	74.67080204592448
2002	74.86668843182066
2003	75.23830273980064
2004	75.74767118810263
2005	75.32821267091573
2006	75.57044055982138
2007	75.67523415377913
2008	75.68067959050316
2009	75.7351339577434
2010	75.73925829112889
2011	75.7773784240048
2012	75.8100528236127
2013	75.8100528236127
2014	75.79916135707673
2015	75.78826989054076
2016	75.78351031966454
2017	75.80477590807602
2018	75.79201655502914
2019	75.75741436584435
2020	75.76853455317757
2021	75.76853455317757