Year	% of land area
1961	61.33177570093458
1962	61.915887850467286
1963	62.46105919003115
1964	62.5
1965	63.2398753894081
1966	63.12305295950156
1967	64.8753894080997
1968	65.26479750778816
1969	73.87071651090342
1970	73.20872274143302
1971	73.94859813084112
1972	74.22118380062305
1973	77.88161993769471
1974	79.04984423676012
1975	80.21806853582555
1976	81.5809968847352
1977	83.45015576323988
1978	82.55451713395638
1979	81.77570093457945
1980	81.30841121495327
1981	80.80218068535827
1982	80.21806853582555
1983	80.21806853582555
1984	80.21806853582555
1985	80.21806853582555
1986	81.07476635514018
1987	81.26947040498442
1988	81.46417445482867
1989	81.26947040498442
1990	81.07476635514018
1991	80.88006230529595
1992	81.07476635514018
1993	80.88006230529595
1994	80.72429906542055
1995	79.32242990654206
1996	77.60903426791276
1997	76.01246105919003
1998	74.49376947040498
1999	73.48130841121495
2000	72.702492211838
2001	72.07943925233646
2002	71.41744548286604
2003	71.3785046728972
2004	71.96261682242991
2005	70.83333333333334
2006	70.95015576323988
2007	71.06697819314641
2008	71.18380062305296
2009	71.3006230529595
2010	71.3785046728972
2011	71.69003115264798
2012	72.42990654205607
2013	73.48130841121495
2014	74.53271028037383
2015	75.58411214953271
2016	76.63551401869158
2017	77.68691588785047
2018	78.73831775700934
2019	79.78971962616822
2020	80.8411214953271
2021	81.89252336448598