Year	% of land area
1961	4.871373836891078
1962	4.871373836891078
1963	4.707170224411604
1964	4.707170224411604
1965	4.433497536945813
1966	4.433497536945813
1967	4.324028461959497
1968	3.6672140120415984
1969	3.6672140120415984
1970	3.6672140120415984
1971	3.6672140120415984
1972	3.8314176245210727
1973	3.8314176245210727
1974	3.8314176245210727
1975	4.105090311986864
1976	4.378762999452655
1977	4.652435686918445
1978	4.926108374384237
1979	4.926108374384237
1980	4.926108374384237
1981	5.199781061850027
1982	5.473453749315818
1983	5.747126436781609
1984	6.0207991242474
1985	6.568144499178982
1986	6.568144499178982
1987	7.1154898741105645
1988	7.662835249042145
1989	8.210180623973727
1990	8.75752599890531
1991	9.35960591133005
1992	9.042145593869732
1993	8.724685276409415
1994	8.407224958949097
1995	7.816091954022989
1996	7.498631636562671
1997	7.1811713191023525
1998	6.863711001642036
1999	6.6557197591680355
2000	6.338259441707718
2001	6.0207991242474
2002	5.703338806787082
2003	5.385878489326766
2004	5.068418171866448
2005	4.75095785440613
2006	4.433497536945813
2007	4.116037219485495
2008	3.7985769020251783
2009	3.3825944170771756
2010	3.4592227695675972
2011	3.535851122058019
2012	3.6124794745484397
2013	3.6891078270388613
2014	3.7657361795292834
2015	3.842364532019704
2016	3.918992884510126
2017	3.9956212370005475
2018	4.072249589490968
2019	4.14887794198139
2020	4.203612479474549
2021	4.203612479474549