Year	% of land area
1961	20.2020202020202
1962	20.2020202020202
1963	20.2020202020202
1964	20.2020202020202
1965	20.2020202020202
1966	20.2020202020202
1967	20.2020202020202
1968	20.2020202020202
1969	20.707070707070706
1970	20.707070707070706
1971	20.707070707070706
1972	20.707070707070706
1973	20.2020202020202
1974	20.2020202020202
1975	20.2020202020202
1976	20.2020202020202
1977	20.2020202020202
1978	19.696969696969695
1979	19.696969696969695
1980	19.696969696969695
1981	19.696969696969695
1982	19.696969696969695
1983	19.19191919191919
1984	19.19191919191919
1985	19.19191919191919
1986	19.19191919191919
1987	19.19191919191919
1988	18.68686868686869
1989	18.68686868686869
1990	18.68686868686869
1991	18.68686868686869
1992	18.68686868686869
1993	18.181818181818183
1994	18.181818181818183
1995	18.181818181818183
1996	18.181818181818183
1997	17.67676767676768
1998	18.68686868686869
1999	19.696969696969695
2000	19.696969696969695
2001	18.68686868686869
2002	18.181818181818183
2003	18.181818181818183
2004	18.68686868686869
2005	19.19191919191919
2006	18.181818181818183
2007	17.17171717171717
2008	18.68686868686869
2009	20.707070707070706
2010	21.767676767676765
2011	22.272727272727273
2012	22.02020202020202
2013	21.262626262626263
2014	21.06060606060606
2015	20
2016	20.151515151515152
2017	19.29292929292929
2018	18.333333333333332
2019	18.333333333333332
2020	18.333333333333332
2021	18.333333333333332