Year	% of land area
1961	15.764976727891497
1962	16.015214453731044
1963	16.36054251538962
1964	18.94299584605375
1965	18.857915019268304
1966	18.897953055402635
1967	18.87793403733547
1968	18.917972073469798
1969	18.917972073469798
1970	18.917972073469798
1971	19.018067163805615
1972	19.26830488964516
1973	19.51854261548471
1974	19.76878034132426
1975	20.14413693008358
1976	20.379360392372753
1977	20.134127421049996
1978	20.419398428507083
1979	20.419398428507083
1980	20.419398428507083
1981	20.61958860917872
1982	20.919873880186177
1983	23.021870777238377
1984	24.022821680596568
1985	24.523297132275662
1986	25.023772583954756
1987	25.023772583954756
1988	25.023772583954756
1989	25.023772583954756
1990	25.023772583954756
1991	25.12386767429058
1992	25.223962764626396
1993	25.223962764626396
1994	25.324057854962213
1995	25.324057854962213
1996	25.324057854962213
1997	25.324057854962213
1998	25.424152945298033
1999	25.52424803563385
2000	26.525198938992045
2001	27.02567439067114
2002	28.02662529402933
2003	29.277813923227065
2004	29.77828937490616
2005	29.77828937490616
2006	30.529002552424807
2007	31.279715729943447
2008	32.280666633301635
2009	33.031379810820276
2010	33.6624775583483
2011	34.16118092958308
2012	34.41053261520048
2013	34.41053261520048
2014	34.41053261520048
2015	34.41053261520048
2016	34.41053261520048
2017	34.41053261520048
2018	34.41053261520048
2019	34.41053261520048
2020	34.41053261520048
2021	34.41053261520048