Year	% of land area
1961	6.172521501065096
1962	6.211556934995411
1963	6.313794963225638
1964	6.358250603905512
1965	6.40265651791796
1966	6.401811164571699
1967	6.426724224952703
1968	6.4786388657466505
1969	6.510861746239446
1970	6.530578369874312
1971	6.528415259841231
1972	6.578738647277509
1973	6.560638140334026
1974	6.5470438051921045
1975	6.559510800837464
1976	6.601822954921197
1977	6.6068886077140325
1978	6.688784488191866
1979	6.686465493483255
1980	6.699661723242719
1981	6.699257268064476
1982	6.728669901260483
1983	6.744834910499504
1984	6.775013359507658
1985	6.856441793970284
1986	6.882542517447423
1987	6.898891526367387
1988	6.958056601148306
1989	6.978542999613015
1990	7.067057716752977
1991	7.117790679275753
1992	7.117828266961695
1993	7.283329731257063
1994	7.293292504997923
1995	7.442407647744988
1996	7.564216690871065
1997	7.616194531233217
1998	7.629329995790064
1999	7.672820262069115
2000	7.674862694975337
2001	7.714237770732575
2002	7.778033290464789
2003	8.024529684170183
2004	8.056772949739562
2005	8.22510696383905
2006	8.310695244265201
2007	8.457687196968191
2008	8.57706686771101
2009	8.759223418651215
2010	8.912860670866174
2011	9.04552965032182
2012	9.270188122586415
2013	9.421496165231057
2014	9.493925437347723
2015	9.572533609564319
2016	9.680054596796385
2017	9.778681806778916
2018	9.847757310643921
2019	9.878858567753559
2020	9.912136891572525
2021	9.949475010391632