Year	% of land area
1961	47.80008137800081
1962	47.603352864583336
1963	47.361282534687845
1964	47.36399517150646
1965	46.993001302083336
1966	46.9624425244483
1967	46.728426877899246
1968	46.69108172261784
1969	46.43336724313327
1970	46.32955346969779
1971	46.15113329625761
1972	45.9313918315858
1973	45.784897521804595
1974	45.70351179414837
1975	45.58550248904684
1976	45.53790643100338
1977	45.478961504028646
1978	45.41866174735157
1979	45.311864130877126
1980	45.184964119538236
1981	45.05941722285528
1982	45.02611408804178
1983	45.05250020348916
1984	45.1800200775972
1985	45.23157066500258
1986	45.24378001465122
1987	45.3550207558944
1988	45.39362120657143
1989	44.518705680984596
1990	44.4861031868938
1991	44.41833616298811
1992	40.40743285248934
1993	39.99612654610089
1994	39.652237497138024
1995	39.15340180472712
1996	39.04850930288747
1997	39.157964846425955
1998	38.589102347725444
1999	38.57789377188275
2000	37.9911110628443
2001	36.19830058580829
2002	35.15664384722546
2003	34.54923637866482
2004	34.18956184621073
2005	34.11765025772191
2006	34.21884162927097
2007	33.38362426473987
2008	33.62393127683309
2009	33.89044069447068
2010	33.08204950227471
2011	33.243670355883715
2012	33.05759972363538
2013	32.93186042344953
2014	33.071969659290986
2015	32.95547728794406
2016	32.76292360907015
2017	32.734392115248205
2018	32.946207624982875
2019	33.36908499593074
2020	32.876372325325285
2021	33.021510693262556