Year	% of land area
1961	35.26716557026159
1962	35.32862763951243
1963	35.439965481788036
1964	35.49367020249265
1965	35.52862799754391
1966	35.536285892903635
1967	35.57348138465091
1968	35.63663415807209
1969	35.67412800937883
1970	35.69737519172088
1971	35.74016492520822
1972	35.828578807997864
1973	35.84743513215638
1974	35.843976030509666
1975	35.880044878728775
1976	35.93141123631131
1977	35.95265720285496
1978	36.03377595763632
1979	36.024563391154665
1980	36.07134480139143
1981	36.13018531123703
1982	36.164390458267476
1983	36.21414064355484
1984	36.24988860877532
1985	36.44967009798052
1986	36.66742336283742
1987	36.79401982286409
1988	37.03459337528539
1989	37.15934491318048
1990	37.23424838572235
1991	37.32799395072666
1992	37.55522437102851
1993	36.93356798159705
1994	37.16952749400159
1995	37.395563748136105
1996	37.592980785290116
1997	37.7804761101053
1998	37.86896600693486
1999	38.06850824376446
2000	38.21609712884586
2001	38.40683039715795
2002	38.51885115273904
2003	38.81632009033832
2004	38.62868930093162
2005	39.051814250166665
2006	39.21569747757062
2007	39.4173518109642
2008	39.53766149830855
2009	39.76131746149934
2010	39.95495809968833
2011	40.11155117588155
2012	40.16370548908399
2013	40.38168312602042
2014	40.499144752967055
2015	40.6486528632559
2016	40.76381976005831
2017	40.89392357634491
2018	41.0459718127847
2019	41.11502334189825
2020	41.19411907692954
2021	41.247263652798345