Year	% of land area
1961	50.57537488104118
1962	50.50489981738213
1963	50.468890660768025
1964	50.4380256693845
1965	50.40201651277039
1966	50.368579438771576
1967	50.32999819954217
1968	50.293989042928054
1969	50.26312405154454
1970	50.22505722883819
1971	49.86650891226626
1972	49.97556521515471
1973	50.10416934591939
1974	50.181846240901265
1975	50.181846240901265
1976	50.181846240901265
1977	50.20756706705419
1978	50.51467373132025
1979	50.4117904267085
1980	50.505414233905185
1981	50.520846729596954
1982	50.574860464518125
1983	51.96635715939196
1984	51.972015741145604
1985	52.077213920111106
1986	52.18292651559968
1987	52.7534144396718
1988	53.01113711772422
1989	53.525039224259885
1990	54.09141181614754
1991	54.607371588775436
1992	54.61920316880578
1993	54.62074641837496
1994	54.62589058360554
1995	54.628462666220834
1996	54.687620566372594
1997	54.687620566372594
1998	54.69533681421848
1999	54.69585123074153
2000	54.697908896833766
2001	54.81108053190668
2002	54.81108053190668
2003	54.81108053190668
2004	54.82136886236786
2005	54.82136886236786
2006	54.82136886236786
2007	54.88824301036549
2008	53.16751974073407
2009	52.82131742071555
2010	52.371202963039174
2011	52.121710949355695
2012	51.70503356567813
2013	51.17724221301988
2014	50.79760281900254
2015	50.76262249543455
2016	50.58669204454848
2017	49.87062424445073
2018	49.64942513953548
2019	49.4385143650814
2020	49.969392216878006
2021	49.9632192186013