Year	% of land area
1961	15.887118952423263
1962	16.014046667089758
1963	16.119819762645175
1964	16.246747477311672
1965	16.37367519197817
1966	16.500602906644666
1967	16.648685240422246
1968	16.75445833597766
1969	16.860231431533077
1970	16.87715512682194
1971	16.982928222377357
1972	17.12466417042161
1973	17.26216919464365
1974	17.516024623976644
1975	17.7593027437541
1976	18.002580863531552
1977	18.286052759620063
1978	18.34317023121999
1979	18.852996551797084
1980	18.891074866197034
1981	18.95453872353028
1982	19.060311819085697
1983	19.16608491464111
1984	19.271858010196528
1985	19.37763110575194
1986	19.52571343952952
1987	19.483404201307355
1988	19.483404201307355
1989	19.441094963085188
1990	19.398785724863025
1991	19.356476486640858
1992	19.37763110575194
1993	19.37763110575194
1994	19.37763110575194
1995	19.37763110575194
1996	19.37763110575194
1997	19.37763110575194
1998	19.37763110575194
1999	19.37763110575194
2000	19.37763110575194
2001	19.37763110575194
2002	19.37763110575194
2003	19.37763110575194
2004	19.483404201307355
2005	19.48975058704068
2006	19.48975058704068
2007	19.48975058704068
2008	19.595523682596095
2009	19.70129677815151
2010	20.519980537750417
2011	20.625753633305834
2012	20.625753633305834
2013	20.625753633305834
2014	20.625753633305834
2015	20.625753633305834
2016	20.625753633305834
2017	20.625753633305834
2018	20.625753633305834
2019	20.625753633305834
2020	20.625753633305834
2021	20.625753633305834