Year	% of land area
1961	0.5367577435783311
1962	0.5562346357488787
1963	0.5607227891620918
1964	0.5780826278358407
1965	0.5887949185296419
1966	0.5904038791872089
1967	0.5823167348294381
1968	0.5890913060191938
1969	0.5999729609927389
1970	0.6068745553923025
1971	0.6156814979389849
1972	0.621778612009765
1973	0.6347349794101728
1974	0.6485914941023607
1975	0.6638034383044944
1976	0.6686304837830115
1977	0.6870918156131294
1978	0.6971269891079412
1979	0.706823422569173
1980	0.7166045410387997
1981	0.7263433170042288
1982	0.7357856954402755
1983	0.7431956336748412
1984	0.758862360227923
1985	0.7832093001414959
1986	0.7940066387118632
1987	0.8003156718372934
1988	0.8146274382560545
1989	0.8214022389276574
1990	0.8300401097839512
1991	0.845791521345428
1992	0.8562924623864125
1993	0.8750501917459131
1994	0.8903358357612172
1995	0.9029115595078802
1996	0.9095593326668906
1997	0.9188746835903445
1998	0.9360152976692865
1999	0.9497261689082295
2000	0.9747848312721072
2001	0.9898083201411733
2002	0.9970831307420934
2003	1.014350772333628
2004	1.0286192028537615
2005	1.0467657269915147
2006	1.0578455011188017
2007	1.0799261437290022
2008	1.0939401008077956
2009	1.1131347926562947
2010	1.1468987312114796
2011	1.1571830264531646
2012	1.163763013606046
2013	1.1907174466812873
2014	1.2232897515670198
2015	1.2729599856051592
2016	1.2667105687797358
2017	1.2876237109480921
2018	1.3519502555215341
2019	1.3738708194624634
2020	1.396472879454212
2021	1.4084860714824403