Year	% of land area
1961	34.863197183417206
1962	34.9815718519857
1963	35.096896418039314
1964	35.20644426049515
1965	35.33611060015663
1966	35.45275239984636
1967	35.561416427977456
1968	35.69899398366763
1969	35.80447964842453
1970	35.94607141871918
1971	36.1237257774743
1972	36.32371638764229
1973	36.5038978083069
1974	36.67121423194928
1975	36.818637116853935
1976	36.80546952302753
1977	37.00385620172173
1978	37.213737191201176
1979	37.37736039037807
1980	37.52798981420073
1981	37.60243664189679
1982	37.8093100024932
1983	38.01518514859052
1984	38.27150003686939
1985	38.58691376738625
1986	38.74645429006527
1987	38.94209854120906
1988	39.09497799207055
1989	39.24835669532753
1990	39.39085659022712
1991	39.504323867159776
1992	36.86002500407799
1993	36.713621507346865
1994	36.81056353118549
1995	36.815353157672874
1996	36.8485946494406
1997	37.04184527414045
1998	37.09825436113014
1999	37.17371556841149
2000	37.195859462262774
2001	37.22517842831648
2002	37.26036727107703
2003	37.160219520620046
2004	37.14563964392709
2005	37.06187735476665
2006	37.110181316821915
2007	37.15687977905707
2008	37.11017430805472
2009	37.14543521878825
2010	37.26148127975937
2011	37.292555733839016
2012	37.301721006948036
2013	37.357106264602514
2014	37.33556392085734
2015	37.382569845963815
2016	37.398702125174104
2017	37.421916887468925
2018	37.43684318898113
2019	37.42425525159611
2020	37.47497627922127
2021	37.479641945236004