Year	% of land area
1961	6.7157712305026
1962	6.7157712305026
1963	6.499133448873485
1964	6.282495667244367
1965	6.282495667244367
1966	6.32582322357019
1967	6.32582322357019
1968	6.369150779896014
1969	6.377816291161179
1970	6.39948006932409
1971	6.421143847487001
1972	6.551126516464471
1973	6.637781629116119
1974	6.7374350086655115
1975	6.793760831889081
1976	6.84575389948007
1977	6.889081455805893
1978	6.923743500866551
1979	6.954072790294627
1980	6.95840554592721
1981	6.971403812824957
1982	7.006065857885615
1983	7.0190641247833625
1984	7.062391681109186
1985	7.084055459272097
1986	7.097053726169844
1987	7.105719237435008
1988	7.1490467937608315
1989	7.1577123050259965
1990	7.192374350086656
1991	7.20103986135182
1992	7.209705372616984
1993	7.214038128249567
1994	7.322357019064126
1995	7.365684575389948
1996	7.365684575389948
1997	7.608318890814559
1998	7.647313691507798
1999	7.681975736568458
2000	7.824956672443674
2001	7.976603119584055
2002	8.128249566724437
2003	8.279896013864818
2004	8.431542461005199
2005	8.60051993067591
2006	8.773830155979203
2007	8.93847487001733
2008	9.116117850953206
2009	9.393414211438476
2010	9.618717504332755
2011	9.863518197573656
2012	9.996750433275563
2013	10.116984402079723
2014	10.116984402079723
2015	10.116984402079723
2016	10.116984402079723
2017	9.787261698440208
2018	9.457538994800693
2019	9.127816291161178
2020	8.799826689774697
2021	8.799826689774697