Year	% of land area
1961	34.45584890540728
1962	34.59453097276381
1963	34.73413006764521
1964	34.873349696850575
1965	35.03338450870888
1966	35.18406550036818
1967	35.31851609838548
1968	35.4747911148225
1969	35.59646660082211
1970	35.794382615273435
1971	36.01106623162601
1972	36.252429584376785
1973	36.477538595971545
1974	36.6915364152992
1975	36.87369824569177
1976	36.83374225642234
1977	37.08642842915155
1978	37.35201579610717
1979	37.55929062623846
1980	37.742636315601345
1981	37.84628660066018
1982	38.11279338207995
1983	38.36624296233079
1984	38.69621614329636
1985	39.062627904926316
1986	39.204473509467576
1987	39.43580364412522
1988	39.57344141367602
1989	39.74768724305928
1990	39.9007592432147
1991	40.023497531612016
1992	36.64706508315384
1993	36.649408637569856
1994	36.72425475895902
1995	36.69449295106302
1996	36.70776671275607
1997	36.90541057369513
1998	36.94861833294407
1999	37.00761028028695
2000	37.00444478103365
2001	37.006921772300736
2002	37.034467028519394
2003	36.85179069052534
2004	36.8855601596668
2005	36.70040051102074
2006	36.72968272869129
2007	36.76818230247561
2008	36.70081560211213
2009	36.70424788583687
2010	36.81734709747996
2011	36.81799313427105
2012	36.833035303958965
2013	36.86432701909012
2014	36.818220831598495
2015	36.863122765037645
2016	36.866335350149065
2017	36.87639447247913
2018	36.87851859613261
2019	36.853394077322335
2020	36.91398148144108
2021	36.91963167345381