Year	% of land area
1961	52.653368310959465
1962	52.60083678502729
1963	52.456042537840105
1964	52.27840375559429
1965	52.09782221646472
1966	52.00377855870167
1967	51.949735426996035
1968	51.740583182983585
1969	51.735242276987336
1970	51.310282271283334
1971	50.74139281088355
1972	50.56945362533675
1973	50.38324412718915
1974	50.257956829690904
1975	50.111806861925515
1976	49.96186411361765
1977	49.90864556496104
1978	49.89582086390803
1979	49.76398253629062
1980	49.63636585692436
1981	49.54911908538125
1982	49.485102931701554
1983	49.17700989893907
1984	49.11722550155647
1985	49.01064439504539
1986	48.9066506137511
1987	48.854180771182605
1988	48.61731147395403
1989	48.49671166590885
1990	48.327904328706005
1991	47.71822515510195
1992	47.11962072950143
1993	47.20165879374629
1994	47.098312550206096
1995	46.67782375964117
1996	46.57641910574997
1997	46.411950424185655
1998	46.26263940186905
1999	46.22360240076158
2000	45.71234700427377
2001	45.16572098361609
2002	44.576923197861674
2003	44.12388430695753
2004	43.842816834930304
2005	43.82473981569916
2006	43.39857901534862
2007	42.865348516269506
2008	43.07182246756158
2009	42.80342437229753
2010	42.404342105122204
2011	42.16269753863107
2012	41.930498964110136
2013	41.81678486651016
2014	41.394902917435076
2015	41.34955124561395
2016	41.10369875529511
2017	41.09412968119552
2018	40.96751377431207
2019	41.3030947284049
2020	40.84980928771564
2021	40.76177146175416