Year	% of land area
1961	8.712629778045205
1962	8.553057804088333
1963	8.084161695999677
1964	7.990873465071045
1965	7.760107841194953
1966	7.632450262029455
1967	7.600535867238081
1968	7.431144079499248
1969	7.490062962191016
1970	7.485153055300035
1971	7.480243148409055
1972	7.431144079499248
1973	7.399229684707874
1974	7.401684638153365
1975	7.369770243361989
1976	7.36240538302552
1977	7.3403108020161065
1978	7.355040522689047
1979	7.3182162210066934
1980	7.303486500333752
1981	7.256842384869435
1982	7.232292850414532
1983	7.210198269405119
1984	7.1905586418411955
1985	7.163554153940802
1986	7.129184805703936
1987	7.084995643685112
1988	7.040806481666285
1989	6.9941623662019685
1990	6.974522738638046
1991	6.841955252581568
1992	6.78794627678078
1993	6.817405718126664
1994	6.817405718126664
1995	6.78549132333529
1996	6.895964228382355
1997	6.864049833590981
1998	6.827225531908626
1999	6.736392254425483
2000	6.3811604908630315
2001	6.576329289779513
2002	6.516673921054098
2003	6.4850050216072725
2004	6.495070330733784
2005	6.596705403377083
2006	6.494579340044685
2007	6.459964496463272
2008	6.418966773923583
2009	6.450881168714957
2010	6.428541092360995
2011	6.3929442674013846
2012	6.367658246912835
2013	6.354941588065195
2014	6.335572005380276
2015	6.322422610909452
2016	6.2988288250952635
2017	6.273123628687922
2018	6.240912341499353
2019	6.236735440286215
2020	6.2328815199923175
2021	6.224582510749145