Year	% of land area
1961	0.17866352317100126
1962	0.18418919914536214
1963	0.21488739900292247
1964	0.2455855988604828
1965	0.2762837987180432
1966	0.2762837987180432
1967	0.3069819985756035
1968	0.3069819985756035
1969	0.3376801984331639
1970	0.3376801984331639
1971	0.35180137036764164
1972	0.35180137036764164
1973	0.3560991183477001
1974	0.36223875831921215
1975	0.36223875831921215
1976	0.38065767823374835
1977	0.44450993393747396
1978	0.41442569807706475
1979	0.43837029396596183
1980	0.4494216459146836
1981	0.44819371792038115
1982	0.44573786193177634
1983	0.49731083769247775
1984	0.5464279574645743
1985	0.5955450772366708
1986	0.6446621970087674
1987	0.6937793167808639
1988	0.7926275203222083
1989	0.7981531962965691
1990	0.8042928362680812
1991	0.8079766202509884
1992	0.8092045482452909
1993	0.8104324762395932
1994	0.8104324762395932
1995	0.8104324762395932
1996	0.8165721162111055
1997	0.8165721162111055
1998	0.8288513961541295
1999	0.8288513961541295
2000	0.8349910361256416
2001	0.836218964119944
2002	0.868759055968958
2003	0.9012991478179719
2004	0.9338392396669859
2005	0.9663793315159999
2006	0.9989194233650139
2007	1.0314595152140278
2008	1.005059063336526
2009	1.0088656401188634
2010	1.0267933888356788
2011	1.0447211375524939
2012	1.0626488862693093
2013	1.0989955549006607
2014	1.0989955549006607
2015	1.0989955549006607
2016	1.0989955549006607
2017	1.1241910631741139
2018	1.1445300462249615
2019	1.1654853620955317
2020	1.1654853620955317
2021	1.1654853620955317