Year	% of land area
1961	16.81329423264907
1962	17.595307917888565
1963	17.595307917888565
1964	18.57282502443793
1965	20.13685239491691
1966	20.13685239491691
1967	21.114369501466275
1968	22.09188660801564
1969	22.482893450635384
1970	22.971652003910066
1971	23.46041055718475
1972	23.46041055718475
1973	23.46041055718475
1974	23.16715542521994
1975	22.87390029325513
1976	22.58064516129032
1977	22.28739002932551
1978	21.896383186705766
1979	21.50537634408602
1980	20.527859237536656
1981	20.527859237536656
1982	20.332355816226784
1983	20.332355816226784
1984	20.332355816226784
1985	19.941348973607038
1986	19.550342130987293
1987	18.377321603128056
1988	18.181818181818183
1989	17.98631476050831
1990	17.888563049853374
1991	17.6930596285435
1992	17.595307917888565
1993	17.595307917888565
1994	17.595307917888565
1995	17.595307917888565
1996	17.888563049853374
1997	18.084066471163247
1998	18.27956989247312
1999	12.609970674486803
2000	12.609970674486803
2001	11.730205278592376
2002	12.70772238514174
2003	13.294232649071358
2004	13.32355816226784
2005	13.851417399804497
2006	13.294232649071358
2007	13.118279569892474
2008	12.023460410557185
2009	12.023460410557185
2010	11.143695014662756
2011	12.218963831867057
2012	12.903225806451612
2013	12.903225806451612
2014	12.903225806451612
2015	13.000977517106548
2016	13.391984359726294
2017	13.408602150537636
2018	13.409579667644184
2019	13.225806451612904
2020	13.421309872922777
2021	13.61681329423265