Year	% of land area
1961	5.7923497267759565
1962	5.901639344262295
1963	6.0109289617486334
1964	6.120218579234972
1965	6.229508196721312
1966	6.33879781420765
1967	6.448087431693988
1968	6.5136612021857925
1969	6.666666666666667
1970	6.775956284153005
1971	6.885245901639345
1972	6.994535519125683
1973	7.103825136612022
1974	7.213114754098362
1975	7.3224043715847
1976	7.431693989071038
1977	7.540983606557377
1978	7.650273224043716
1979	7.759562841530054
1980	7.846994535519125
1981	7.9344262295081975
1982	8.021857923497269
1983	8.109289617486338
1984	8.19672131147541
1985	8.284153005464482
1986	8.371584699453551
1987	8.469945355191257
1988	8.568306010928962
1989	8.622950819672132
1990	8.53551912568306
1991	8.448087431693988
1992	8.360655737704919
1993	8.273224043715848
1994	8.218579234972678
1995	8.163934426229508
1996	7.978142076502732
1997	7.737704918032787
1998	7.754098360655738
1999	7.770491803278688
2000	8.624590163934426
2001	8.548415300546448
2002	8.44120218579235
2003	8.349180327868853
2004	8.250273224043715
2005	8.193178091177435
2006	8.103749863343172
2007	7.991691264895594
2008	7.904230895375533
2009	7.751937984496124
2010	7.795610874549623
2011	7.882956654656621
2012	7.99213887979037
2013	8.143642500644068
2014	8.178102648746364
2015	8.211615883745099
2016	8.306806570777333
2017	8.411744478503499
2018	8.555291379566315
2019	9.409770800038425
2020	9.476063690429406
2021	9.459881273633926