Year	% of land area
1961	30.51473018531168
1962	30.541171804420156
1963	31.369675869819094
1964	31.34103078245158
1965	31.364167199171497
1966	31.554767203578432
1967	31.366370667430537
1968	31.67044928717802
1969	32.94074873851442
1970	32.45268051913712
1971	32.655399598968785
1972	33.31754181081021
1973	33.28448978692462
1974	32.84930480576427
1975	32.42183196351056
1976	32.36564352290505
1977	32.58929555119759
1978	32.64658572593262
1979	33.336271291012046
1980	32.79421809928828
1981	32.93634180199634
1982	31.516206509045237
1983	30.955423837119632
1984	31.837912874865037
1985	31.943679351298943
1986	31.912830795672388
1987	32.367846991164086
1988	32.188264328052355
1989	32.29182733622723
1990	32.04063195469669
1991	32.06927704206421
1992	11.207764328997767
1993	11.104598537994868
1994	11.056588849399619
1995	11.017776578208935
1996	10.878913237668996
1997	10.910914962340536
1998	10.796476805257738
1999	10.728394364024052
2000	10.591274943014431
2001	10.517888663608739
2002	10.449173514132013
2003	10.37229677985049
2004	10.362652355340913
2005	10.333412388550531
2006	10.36323636078007
2007	10.315357765924896
2008	10.294706725424561
2009	10.289045839033637
2010	10.291755013674063
2011	10.27636835186416
2012	10.28300903907112
2013	10.303310508033512
2014	10.312640998990647
2015	10.318117913782588
2016	10.311698015247012
2017	10.299909833715224
2018	10.290589596007118
2019	10.269275104421888
2020	10.277057540506364
2021	10.29480640191901