Year	% of land area
1961	36.643954772904095
1962	36.70710798369901
1963	36.75430015325363
1964	36.80308151739062
1965	36.81904255863092
1966	36.800732273225385
1967	36.825606623210255
1968	36.898571383165866
1969	36.96124092604441
1970	36.91349599315679
1971	36.9480437014691
1972	37.04159889557886
1973	37.07761142672362
1974	37.04347258287188
1975	37.068335689617285
1976	37.121383173230406
1977	37.13921077616408
1978	37.168785249247854
1979	37.186405554473
1980	37.24748927925351
1981	37.235949706811944
1982	37.25681767613741
1983	37.31396274445582
1984	37.30898759945108
1985	37.46411538466854
1986	37.72572509283482
1987	37.839946130235475
1988	38.081586159146596
1989	38.21052533385296
1990	38.33925721085079
1991	38.44373801991993
1992	38.59236358083298
1993	37.62615367393729
1994	37.861372988002984
1995	38.067488339503896
1996	38.247640730959354
1997	38.45346657048053
1998	38.58666990051091
1999	38.77140279741348
2000	38.97689157086058
2001	39.206973218518044
2002	39.3267823318781
2003	39.7248937343445
2004	39.41927914488159
2005	39.90499917606242
2006	40.089084134084004
2007	40.264026599186515
2008	40.31958947264292
2009	40.54884522660836
2010	40.78322247716749
2011	40.985282553679355
2012	41.01302226730279
2013	41.20762314652534
2014	41.33497843758952
2015	41.42486231206527
2016	41.57289655924411
2017	41.709459838522164
2018	41.81812883388412
2019	41.8764706141354
2020	41.94974060597229
2021	41.989058891640774