Year	% of land area
1961	0.009480692291304866
1962	0.009480692291304866
1963	0.009480692291304866
1964	0.009480692291304866
1965	0.009480692291304866
1966	0.009703767404041452
1967	0.00959222984767316
1968	0.009480692291304866
1969	0.009369154734936574
1970	0.009257617178568283
1971	0.009146079622199989
1972	0.009257617178568283
1973	0.009369154734936574
1974	0.009480692291304866
1975	0.00959222984767316
1976	0.00971492115967828
1977	0.009815304960409745
1978	0.009815304960409745
1979	0.009815304960409745
1980	0.009815304960409745
1981	0.009966159505397861
1982	0.010261455185882914
1983	0.0104845302986195
1984	0.010707605411356085
1985	0.01093068052409267
1986	0.011253247137109772
1987	0.011488368305934133
1988	0.011711443418670718
1989	0.011934518531407302
1990	0.012157593644143887
1991	0.012416026162249223
1992	0.013719119433299983
1993	0.015057570109719493
1994	0.016396020786139005
1995	0.017734471462558514
1996	0.019160222584347488
1997	0.018961384582609733
1998	0.01884984702624144
1999	0.01873830946987315
2000	0.018626771913504855
2001	0.018403696800768272
2002	0.018403696800768272
2003	0.018403696800768272
2004	0.018403696800768272
2005	0.018403696800768272
2006	0.018476341211230936
2007	0.01873830946987315
2008	0.019072922138978026
2009	0.019407534808082903
2010	0.019742147477187784
2011	0.01993176132301388
2012	0.019965222589924364
2013	0.019965222589924364
2014	0.019965222589924364
2015	0.019965222589924364
2016	0.019853685033556074
2017	0.01929599725171461
2018	0.018961384582609733
2019	0.018626771913504855
2020	0.018626771913504855
2021	0.019570584955681727