Year	% of land area
1961	9.33664275271157
1962	9.435245316378225
1963	9.319642310700079
1964	9.438645404780525
1965	9.44544558158512
1966	9.567848764067865
1967	9.60184964809085
1968	9.68685185814831
1969	9.452245758389719
1970	10.016660433171262
1971	9.853456189860935
1972	9.901057427493114
1973	10.013260344768964
1974	10.094862466424127
1975	10.142463704056306
1976	10.162864234470097
1977	10.118663085240216
1978	10.101662643228725
1979	10.098262554826427
1980	10.040461051987352
1981	10.057461493998844
1982	10.054061405596546
1983	10.676277583217164
1984	10.65927714120567
1985	10.417870864642481
1986	10.24106626772296
1987	10.217265648906872
1988	10.278467240148244
1989	10.111862908435619
1990	10.064261670803441
1991	10.030260786780456
1992	9.788854510217265
1993	9.62225017850464
1994	9.567848764067865
1995	8.993233824079425
1996	9.091836387746081
1997	9.251640542654108
1998	9.547448233654075
1999	9.782054333412669
2000	9.485388106236346
2001	9.46171690597123
2002	8.81583129873731
2003	8.724528097714716
2004	8.623080096578498
2005	8.636606496729993
2006	8.606172096389129
2007	8.558829695858892
2008	8.600085216320954
2009	8.719117537654117
2010	8.75090457801013
2011	8.523661055465004
2012	8.257867292488113
2013	7.642416085595061
2014	8.09216889063229
2015	8.274775292677482
2016	8.291683292866853
2017	8.39313129400307
2018	8.240959292298744
2019	8.166209585515883
2020	7.38934860018193
2021	7.333438726890913