Year	% of land area
1961	53.303607620591805
1962	53.70895824888529
1963	54.114308877178765
1964	54.51965950547223
1965	54.9250101337657
1966	55.330360762059186
1967	55.73571139035266
1968	56.05999189298744
1969	56.62748277259829
1970	56.91122821240373
1971	58.694770976895015
1972	61.12687474665586
1973	61.00526955816782
1974	64.20753952168626
1975	65.34252128090799
1976	66.43696797730037
1977	67.4908796108634
1978	68.09890555330361
1979	68.78800162140251
1980	69.51763275233077
1981	71.34171057965139
1982	71.94973652209161
1983	72.55776246453182
1984	73.28739359546007
1985	73.7332792865829
1986	74.17916497770571
1987	74.66558573165788
1988	75.11147142278071
1989	75.15200648561006
1990	76.1248479935144
1991	76.00324280502635
1992	74.38184029185246
1993	71.13903526550466
1994	62.82934738548845
1995	62.82934738548845
1996	64.89663558978516
1997	66.92338873125253
1998	67.73408998783948
1999	69.59870287798947
2000	74.01702472638833
2001	76.895014187272
2002	76.53019862180787
2003	76.44912849614917
2004	76.32752330766112
2005	76.24645318200243
2006	76.36805837049047
2007	76.1248479935144
2008	76.20591811917309
2009	77.25982975273612
2010	77.90839075800568
2011	78.75962707742197
2012	79.40818808269154
2013	80.25942440210783
2014	81.31333603567086
2015	81.3538710985002
2016	81.27280097284151
2017	81.27280097284151
2018	79.00283745439806
2019	77.17875962707743
2020	79.39197405755979
2021	81.25091203891365