Year	% of land area
1961	0.24939749930722918
1962	0.25191666596689816
1963	0.25611527706634646
1964	0.2607337492757396
1965	0.24393930487794638
1966	0.23638180489893942
1967	0.2372215271188291
1968	0.22840444380998765
1969	0.23260305490943595
1970	0.2317633326895463
1971	0.252336527076843
1972	0.252336527076843
1973	0.2615734714956292
1974	0.2615734714956292
1975	0.27290972146413967
1976	0.27458916590391896
1977	0.2678713881448017
1978	0.27290972146413967
1979	0.27332958257408446
1980	0.26619194370502236
1981	0.2624131937155189
1982	0.2636727770453534
1983	0.26829124925474657
1984	0.24981736041717398
1985	0.252336527076843
1986	0.23764138822877393
1987	0.2330229160193808
1988	0.22714486048015314
1989	0.22840444380998765
1990	0.23260305490943595
1991	0.22924416602987732
1992	0.22336611049064967
1993	0.2229462493807049
1994	0.22210652716081522
1995	0.21412916607186344
1996	0.21790791606136692
1997	0.2137093049619186
1998	0.21538874940169794
1999	0.21790791606136692
2000	0.22252638827076004
2001	0.24351944376800155
2002	0.2766884714536431
2003	0.3111170824691192
2004	0.3371484712856987
2005	0.35772166567299535
2006	0.38123388782990586
2007	0.38669208225918866
2008	0.38249347115974036
2009	0.3803941656100162
2010	0.3816537489398507
2011	0.385852360039299
2012	0.38795166558902316
2013	0.39424958223819556
2014	0.4071813044244964
2015	0.41998689194165106
2016	0.42548707017261744
2017	0.42515915878342775
2018	0.4180954184355058
2019	0.4110316780875838
2020	0.4110316780875838
2021	0.4110316780875838