Year	% of land area
1961	8.133948456888323
1962	8.16576519249125
1963	8.261215399300031
1964	8.261215399300031
1965	8.40598154629335
1966	8.421889914094814
1967	8.31053133948457
1968	8.294622971683106
1969	8.35825644288896
1970	8.461660833598472
1971	8.469615017499205
1972	8.62869869551384
1973	8.708240534521158
1974	8.80369074132994
1975	8.994591154947502
1976	9.280941775373847
1977	9.503658924594337
1978	9.678650970410436
1979	9.845688832325804
1980	9.949093223035316
1981	10.203627107858734
1982	10.426344257079224
1983	10.626789691377665
1984	10.839961819917276
1985	11.110404072542158
1986	11.291759465478842
1987	11.51924912503977
1988	11.858097359210944
1989	11.765828825962457
1990	12.048997772828507
1991	12.347352024922118
1992	12.30373831775701
1993	12.213395638629283
1994	12.138629283489097
1995	12.157320872274143
1996	12.098130841121495
1997	11.99221183800623
1998	11.933021806853583
1999	11.886292834890966
2000	11.76791277258567
2001	11.719626168224298
2002	11.66043613707165
2003	11.632398753894082
2004	11.542056074766355
2005	11.576323987538942
2006	11.566978193146417
2007	11.498442367601246
2008	11.43146417445483
2009	11.366043613707165
2010	11.551401869158878
2011	11.688473520249222
2012	11.809968847352025
2013	11.892523364485982
2014	12.021806853582554
2015	12.176323987538941
2016	12.074922118380062
2017	12.014029618082619
2018	11.896648480124707
2019	11.795946999220577
2020	11.777240841777084
2021	11.777240841777084