Year	% of land area
1961	15.434960458140168
1962	15.325879465503137
1963	15.189528224706844
1964	15.080447232069814
1965	14.93864194164167
1966	14.870466321243523
1967	14.663212435233161
1968	14.507772020725387
1969	14.076902099809107
1970	14.169620943550587
1971	13.976002181619855
1972	13.794326241134753
1973	13.6797599563557
1974	13.578832515002729
1975	13.4924965893588
1976	13.427012278308323
1977	13.403384279475983
1978	13.367903930131003
1979	13.324235807860262
1980	13.306033306033305
1981	13.266921397379914
1982	13.249590387766247
1983	13.225013653741124
1984	13.260213874417328
1985	13.24739440482721
1986	13.216342199067727
1987	13.203510696653867
1988	13.181568842567195
1989	13.143170597915525
1990	13.077345035655513
1991	13.000548546352167
1992	12.929237520570489
1993	12.849698299506308
1994	12.781130005485464
1995	12.69884805266045
1996	12.625514403292183
1997	12.534979423868311
1998	12.441700960219478
1999	12.353909465020577
2000	12.27434842249657
2001	12.192043895747599
2002	12.123456790123457
2003	12.063100137174212
2004	12.013717421124829
2005	11.96159122085048
2006	11.914951989026063
2007	11.868312757201647
2008	11.818930041152264
2009	11.780521262002743
2010	11.747599451303154
2011	11.670781893004115
2012	11.648834019204388
2013	11.626886145404663
2014	11.582990397805212
2015	11.536351165980797
2016	11.478737997256516
2017	11.415637860082304
2018	11.363511659807957
2019	11.314128943758574
2020	11.25925925925926
2021	11.209876543209877