Year	% of land area
1961	70.32402842473904
1962	70.21862568426779
1963	69.73581313114141
1964	69.5726088878311
1965	69.49780694298052
1966	69.37880384890008
1967	69.29040155044031
1968	69.20879942878516
1969	68.77358811329096
1970	68.61378395838292
1971	60.00816021216552
1972	59.528747747441436
1973	59.44034544898167
1974	59.50834721702765
1975	59.55934854306212
1976	59.6001496038897
1977	59.50494712862534
1978	59.804154908027606
1979	59.86875658767128
1980	59.71235252116555
1981	59.67495154874026
1982	59.62395022270579
1983	58.68552582367141
1984	58.63112440923464
1985	58.12451123729217
1986	57.94430655197035
1987	57.842303899901395
1988	57.25408860630377
1989	57.29148957872905
1990	57.25748869470606
1991	54.585019210499475
1992	54.326612491924784
1993	54.0954064805685
1994	53.388188092890424
1995	52.13355547244228
1996	52.187956886879064
1997	52.17435653326986
1998	52.646968821189354
1999	53.71799666791337
2000	52.87807979223449
2001	52.421563787121514
2002	51.64717737844838
2003	50.40951176458653
2004	50.32835336367756
2005	49.83125815811009
2006	48.02886533792329
2007	47.89021973637046
2008	48.888468067550846
2009	47.28288436956831
2010	48.45088902264996
2011	46.843952684652265
2012	46.42598691997105
2013	46.091208516221535
2014	44.508619698496545
2015	43.774812490277895
2016	43.32505968524067
2017	43.374329597792496
2018	41.94874846982598
2019	44.369995637721196
2020	42.332263616904
2021	41.94223159304335