Year	% of land area
1961	36.39026007514919
1962	36.40192539109506
1963	36.43876323092414
1964	36.475601070753214
1965	36.51243891058228
1966	36.51857855055379
1967	36.56155603035438
1968	36.59225423021194
1969	36.63523171001252
1970	36.65365062992706
1971	36.93239028463371
1972	37.32901102679339
1973	37.74712050885336
1974	37.427245266337586
1975	37.107983987818955
1976	36.80714162921486
1977	36.649352881947
1978	36.142218620300106
1979	36.78135514133451
1980	35.433704167587614
1981	35.781821753972345
1982	36.142218620300106
1983	36.35280827132297
1984	36.55541639038287
1985	37.06500650801837
1986	37.26761462707827
1987	37.47022274613816
1988	37.986566467742335
1989	37.881578624229476
1990	37.75878582479923
1991	38.67788992853459
1992	39.16292148628405
1993	39.387018345244236
1994	39.39008816522999
1995	39.421400329084705
1996	39.55585844446082
1997	39.19054986615585
1998	39.77688548343525
1999	39.10152508656892
2000	38.60851199685651
2001	39.18502419018149
2002	39.32071023355191
2003	39.45639627692232
2004	39.59208232029274
2005	29.243719148309143
2006	29.37940519167956
2007	29.51509123504998
2008	28.662909207004102
2009	28.663645963800683
2010	28.573516049018888
2011	28.483386134237087
2012	28.393256219455292
2013	28.214101525086573
2014	28.214101525086573
2015	28.214101525086573
2016	28.214101525086573
2017	28.619414483821267
2018	28.915254237288135
2019	28.9604519568567
2020	28.984694422187985
2021	29.00893682588598