Year	% of land area
1961	69.44757609921083
1962	67.75648252536641
1963	68.20744081172492
1964	65.95264937993235
1965	68.65839909808342
1966	65.50169109357384
1967	64.03607666290868
1968	63.81059751972943
1969	63.35963923337091
1970	62.232243517474636
1971	59.75197294250282
1972	58.060879368658405
1973	55.46786922209696
1974	55.69334836527621
1975	55.58060879368658
1976	55.58060879368658
1977	55.35512965050733
1978	55.80608793686584
1979	54.79143179255919
1980	53.551296505073275
1981	52.649379932356254
1982	52.649379932356254
1983	52.536640360766626
1984	52.311161217587376
1985	51.97294250281848
1986	52.19842164599775
1987	52.08568207440811
1988	52.08568207440811
1989	50.732807215332585
1990	49.04171364148816
1991	47.350620067643746
1992	46.22322435174747
1993	35.062006764374296
1994	34.83652762119504
1995	34.83652762119504
1996	34.83652762119504
1997	32.807215332581734
1998	30.721533258173615
1999	29.301014656144307
2000	27.86922209695603
2001	26.45997745208568
2002	25.02818489289741
2003	24.30665163472379
2004	23.562570462232244
2005	22.818489289740697
2006	22.074408117249156
2007	21.307779030439683
2008	21.49943630214205
2009	21.679819616685457
2010	21.860202931228862
2011	22.040586245772268
2012	22.18714768883878
2013	21.668545659526494
2014	21.149943630214203
2015	20.631341600901916
2016	20.11273957158963
2017	19.59413754227734
2018	19.041713641488162
2019	19.041713641488162
2020	19.041713641488162
2021	19.041713641488162