Year	% of land area
1961	0.9351362863029334
1962	0.9348969986145242
1963	0.9345380670819106
1964	0.9342987793935014
1965	0.9340594917050922
1966	0.9338202040166832
1967	0.933580916328274
1968	0.9333416286398648
1969	0.9331023409514557
1970	0.9552364521293014
1971	0.9648079596656672
1972	0.9743794672020331
1973	0.9840706185826033
1974	0.9936421261189691
1975	1.0032136336553348
1976	1.0531051166886412
1977	1.1031162435661523
1978	1.1530077265994587
1979	1.2030188534769697
1980	1.2529103365102763
1981	1.2483638704305025
1982	1.2438174043507289
1983	1.239270938270955
1984	1.2347244721911814
1985	1.1848329891578748
1986	1.166048905617757
1987	1.1471451782334348
1988	1.128361094693317
1989	1.1094573673089947
1990	1.0906732837688768
1991	1.071889200228759
1992	1.0529854728444368
1993	1.034201389304319
1994	1.0152976619199965
1995	0.9023538729908808
1996	0.9473399584117997
1997	0.9923260438327187
1998	1.0373121292536378
1999	1.0822982146745568
2000	1.1272843000954758
2001	1.1722703855163947
2002	1.217256470937314
2003	1.262242556358233
2004	1.3072286417791519
2005	1.3522147272000709
2006	1.3973204564651944
2007	1.3546076040841621
2008	1.3120143955473347
2009	1.2693015431663024
2010	1.2265886907852706
2011	1.1839954822484429
2012	1.1412826298674108
2013	1.0986894213305831
2014	1.055976568949551
2015	1.0132637165685188
2016	0.9706705080316912
2017	0.9279337268818182
2018	0.9279576556506592
2019	0.9279576556506592
2020	0.9279576556506592
2021	0.9279576556506592