Year	% of land area
1961	27.320799059929495
1962	27.614571092831962
1963	27.810419114766944
1964	29.0834312573443
1965	30.454367410889148
1966	32.02115158636898
1967	32.04073638856247
1968	33.607520564042304
1969	35.05679592636115
1970	36.349392871132004
1971	36.95652173913043
1972	36.95652173913043
1973	40.109674892283586
1974	40.109674892283586
1975	41.55895025460243
1976	43.18448883666275
1977	44.790442616529575
1978	46.22013317665491
1979	47.845671758715234
1980	49.275362318840585
1981	50.9009009009009
1982	52.46768507638073
1983	52.526439482961216
1984	53.81903642773208
1985	52.506854680767724
1986	51.155503329416376
1987	49.725812769291025
1988	48.2373678025852
1989	46.57265961613788
1990	43.05914610262436
1991	43.157422640031335
1992	42.30317273795535
1993	41.38268703486095
1994	41.030160595377986
1995	40.109674892283586
1996	39.0716803760282
1997	38.249118683901294
1998	37.50489620054837
1999	36.97610654132394
2000	36.03603603603604
2001	35.89894242068155
2002	35.76184880532707
2003	35.82060321190756
2004	35.68350959655307
2005	35.350567959263614
2006	35.54641598119859
2007	35.25264394829612
2008	35.11555033294164
2009	35.566000783392084
2010	35.62475518997258
2011	35.62475518997258
2012	35.487661574618095
2013	35.27222875048962
2014	34.95887191539365
2015	35.086173129651385
2016	34.80219349784567
2017	34.88053270661967
2018	34.909909909909906
2019	34.78260869565217
2020	34.97845671758715
2021	35.4680767724246