Year	% of land area
1961	15.901060070671377
1962	15.901060070671377
1963	15.901060070671377
1964	15.901060070671377
1965	17.6678445229682
1966	17.6678445229682
1967	17.6678445229682
1968	17.6678445229682
1969	17.6678445229682
1970	17.6678445229682
1971	17.6678445229682
1972	17.6678445229682
1973	17.6678445229682
1974	17.6678445229682
1975	17.6678445229682
1976	18.727915194346288
1977	19.434628975265017
1978	19.434628975265017
1979	20.141342756183743
1980	20.141342756183743
1981	21.20141342756184
1982	21.20141342756184
1983	21.20141342756184
1984	21.20141342756184
1985	21.20141342756184
1986	21.20141342756184
1987	20.49469964664311
1988	20.49469964664311
1989	11.908127208480565
1990	11.66077738515901
1991	11.66077738515901
1992	11.66077738515901
1993	11.66077738515901
1994	11.307420494699647
1995	11.307420494699647
1996	11.307420494699647
1997	11.307420494699647
1998	11.307420494699647
1999	11.307420494699647
2000	10.954063604240282
2001	10.954063604240282
2002	10.954063604240282
2003	10.247349823321555
2004	9.89399293286219
2005	9.540636042402827
2006	9.11660777385159
2007	8.657243816254418
2008	8.12720848056537
2009	7.773851590106007
2010	8.303886925795052
2011	8.8339222614841
2012	9.363957597173144
2013	9.89399293286219
2014	10.424028268551238
2015	10.982332155477032
2016	11.445229681978798
2017	12.122302158273381
2018	12.589928057553957
2019	11.406474820143885
2020	11.406474820143885
2021	11.406474820143885