Year	% of land area
1961	72.82784051624799
1962	72.80479373127449
1963	72.82784051624799
1964	73.13513098256126
1965	74.03395559652762
1966	74.13382499807943
1967	74.47952677268188
1968	74.27978796957825
1969	74.32588153952524
1970	74.49489129599755
1971	74.47952677268188
1972	76.75347622340017
1973	76.73811170008452
1974	76.73811170008452
1975	76.85334562495198
1976	76.807252055005
1977	76.75347622340017
1978	76.72274717676885
1979	76.69201813013751
1980	76.72274717676885
1981	76.67665360682184
1982	76.65360682184836
1983	76.54605515863871
1984	77.28355227779058
1985	77.03003764308212
1986	77.13758930629177
1987	77.70607666897135
1988	80.10294230621496
1989	80.22585849274026
1990	79.78796957824383
1991	79.28094030882691
1992	73.3579165706384
1993	72.56664361988169
1994	71.89060459399246
1995	72.01352078051778
1996	71.65245448259968
1997	71.9443804255973
1998	72.47445647998771
1999	72.87393408619498
2000	72.21325958362141
2001	72.23630636859491
2002	71.85219328570331
2003	71.66013674425751
2004	71.62172543596836
2005	71.52953829607436
2006	71.29138818468157
2007	71.18383652147192
2008	71.0839671199201
2009	71.03019128831528
2010	70.99177998002611
2011	70.1236844126911
2012	70.08527310440194
2013	71.27602366136591
2014	71.59867865099486
2015	72.47630022278558
2016	73.1136974725359
2017	73.45263885687947
2018	73.95943765844665
2019	75.83928708611816
2020	76.26949373895675
2021	77.34501037105323