Year	% of land area
1961	33.94145099703012
1962	35.00212134068732
1963	35.53245651251591
1964	36.06279168434451
1965	38.2159524819686
1966	38.746287653797204
1967	38.237165888841744
1968	39.31904963937208
1969	39.84938481120068
1970	39.31904963937208
1971	40.91005515485787
1972	41.44039032668647
1973	41.97072549851506
1974	42.002545608824775
1975	41.47221043699618
1976	41.49342384386932
1977	41.52524395417904
1978	42.08739923631735
1979	42.1086126431905
1980	40.62367416207043
1981	41.68434450572762
1982	42.74501484938481
1983	41.79041154009334
1984	42.320746711921934
1985	42.47984726347052
1986	43.540517607127704
1987	43.593551124310565
1988	43.646584641493426
1989	44.176919813322016
1990	44.73907509546033
1991	45.82095884599067
1992	45.29062367416207
1993	45.29062367416207
1994	43.16928298684769
1995	45.396690708527785
1996	46.45736105218498
1997	46.987696224013575
1998	48.578701739499365
1999	49.63937208315656
2000	50.169707254985155
2001	51.23037759864234
2002	51.23037759864234
2003	52.82138311412813
2004	52.82138311412813
2005	54.94272380144252
2006	56.05642766228256
2007	56.05642766228256
2008	57.64743317776835
2009	58.177768349596946
2010	58.177768349596946
2011	58.177768349596946
2012	58.177768349596946
2013	58.81417055579126
2014	59.93848112006789
2015	60.52184980907934
2016	61.115825201527365
2017	61.699193890538815
2018	62.29316928298685
2019	62.8765379719983
2020	63.47051336444633
2021	64.17055579126007