Year	% of land area
1961	3.3853113823059715
1962	3.386927668475609
1963	3.4036782705973083
1964	3.4315224732469742
1965	3.4656114179156945
1966	3.457383051961176
1967	3.4785417072727953
1968	3.4706806790841034
1969	3.4880924891842904
1970	3.508589936517422
1971	3.530336332254364
1972	3.571037356707966
1973	3.5794231766273166
1974	3.608883752022476
1975	3.6136591570117162
1976	3.6534052200760083
1977	3.645103362171637
1978	3.6625886912091628
1979	3.6544337688429214
1980	3.6476747340889197
1981	3.671742775234691
1982	3.68612335635152
1983	3.6741774971015126
1984	3.7092671729624502
1985	3.73148676503854
1986	3.7550699189084806
1987	3.7916715614567806
1988	3.800267290437413
1989	3.8098034068620805
1990	3.8518563578750213
1991	3.904253570772347
1992	3.965195136352673
1993	4.140356733983371
1994	4.123481917514772
1995	4.200141241578494
1996	4.246095836653765
1997	4.2171505112137
1998	4.194541889093072
1999	4.1700685107980195
2000	4.127870398049992
2001	4.112148010007177
2002	4.129580725200753
2003	4.276272394065762
2004	4.2238931630113665
2005	4.237461046012596
2006	4.243998267323405
2007	4.28240036922179
2008	4.2203561280258866
2009	4.231123893007416
2010	4.243070102388723
2011	4.247314787136703
2012	4.436734791861676
2013	4.4568405480068565
2014	4.44356296543954
2015	4.474376826643934
2016	4.539178807206945
2017	4.595220162848373
2018	4.585629579204746
2019	4.528386325025892
2020	4.613973093799351
2021	4.583450751986995