Year	% of land area
1961	0.8166026968587838
1962	0.8199968617884912
1963	0.8232797426221427
1964	0.826840833695934
1965	0.8275085382722699
1966	0.8304019247697254
1967	0.8348532886119646
1968	0.8375797489653362
1969	0.8511007666361378
1970	0.8591132215521683
1971	0.8752494154802855
1972	0.8843747113568758
1973	0.8927766606091023
1974	0.8994870916012779
1975	0.9010116837172449
1976	0.9259460190330566
1977	0.954379311246619
1978	0.9816441119993501
1979	1.0125534932608646
1980	1.0460780696966208
1981	1.061296279912686
1982	1.0603781794791756
1983	1.063299408131254
1984	1.0678899102988055
1985	1.053005554785835
1986	1.053083454216557
1987	1.0604477325423203
1988	1.0548695768781136
1989	1.0509050522788643
1990	1.0481090191404465
1991	1.0580551071701418
1992	1.0602112521276281
1993	1.0591401349551994
1994	1.0741441217367789
1995	1.0322926525813367
1996	1.033436104939436
1997	1.0606146598938675
1998	1.0929639349488196
1999	1.1114526168660248
2000	1.1332238409533082
2001	1.1512081594301196
2002	1.1602071071874442
2003	1.1566004789769044
2004	1.2159452292388653
2005	1.24964539402367
2006	1.2688742445286147
2007	1.2643145166908645
2008	1.2527776307026075
2009	1.237673784795276
2010	1.2288511323704399
2011	1.2302321930272817
2012	1.2159680457617792
2013	1.2102775159515793
2014	1.205762420687145
2015	1.213363295988709
2016	1.191748517980719
2017	1.1859647900395824
2018	1.210221178485168
2019	1.222527794282757
2020	1.2361107185778317
2021	1.2477425898868229