Year	% of land area
1961	21.307484667995162
1962	21.307484667995162
1963	21.27988429925424
1964	21.27988429925424
1965	21.25228393051331
1966	21.224683561772384
1967	21.224683561772384
1968	21.224683561772384
1969	21.19708319303146
1970	21.19708319303146
1971	21.169482824290533
1972	21.169482824290533
1973	21.141882455549606
1974	21.141882455549606
1975	21.11759413105759
1976	21.0016725823457
1977	21.0016725823457
1978	21.0016725823457
1979	20.976280243104046
1980	20.976280243104046
1981	20.948679874363123
1982	20.948679874363123
1983	20.921079505622195
1984	20.452977251776083
1985	21.903100625424354
1986	22.79348852100664
1987	24.004040693983672
1988	24.36394950236535
1989	24.528447700061275
1990	24.886148478943678
1991	22.92155423196454
1992	22.826056956120933
1993	23.193141860375256
1994	23.16830152850842
1995	23.724172954950678
1996	23.71865288120249
1997	24.02722500372605
1998	24.220427584912535
1999	25.32444233454959
2000	25.127308964649625
2001	25.92517039774298
2002	26.604258066096804
2003	27.23008395654052
2004	27.642862735343826
2005	27.765364824537066
2006	28.367222914921236
2007	28.9158192273953
2008	29.091583094498645
2009	29.4803940732424
2010	29.496372606615434
2011	30.0449689190895
2012	30.060947452462532
2013	30.34323487538608
2014	30.518998742489423
2015	30.78530763203994
2016	31.797281412331913
2017	33.714705417095644
2018	34.03427608455627
2019	34.14079964037647
2020	34.24732319619668
2021	34.1337419293713