Year	% of land area
1961	32.9797312106471
1962	33.31105728270046
1963	33.64848868802644
1964	33.968103147295864
1965	34.34592722113541
1966	34.67853645892783
1967	34.99979020482426
1968	35.33785955913316
1969	35.69615028113995
1970	36.069648011085825
1971	36.506863923939804
1972	36.89079010093055
1973	37.32500535211192
1974	37.788854769087116
1975	38.15642009046469
1976	38.04741019062169
1977	38.548387687193724
1978	39.01532145638451
1979	39.35775944722114
1980	39.77845843816922
1981	40.08935329003507
1982	40.57356437200091
1983	41.10185633537016
1984	41.64954328672579
1985	42.218256507520046
1986	42.41850746479959
1987	42.61596103112157
1988	42.806723427912715
1989	43.011406832499105
1990	43.202071872143264
1991	43.38792165037607
1992	34.774015470970966
1993	34.68645350748711
1994	34.729473886111975
1995	34.5391388341155
1996	34.522192757868986
1997	34.8132799265568
1998	34.815896390670886
1999	34.825234085143215
2000	34.85912988926399
2001	34.76211175221433
2002	34.7434353384594
2003	34.394338736311
2004	34.36837664403618
2005	34.37223936326978
2006	34.394066166000826
2007	34.39116433161125
2008	34.42875293259114
2009	34.439925689897656
2010	34.57018731975286
2011	34.55135834154349
2012	34.55402689252674
2013	34.600051793950584
2014	34.56046191138976
2015	34.57895514313558
2016	34.57171691145203
2017	34.53380590888592
2018	34.51605700606864
2019	34.4611387246103
2020	34.45667589231793
2021	34.42115570929251