Year	% of land area
1961	18.9083820662768
1962	18.9083820662768
1963	19.103313840155945
1964	19.103313840155945
1965	19.103313840155945
1966	19.103313840155945
1967	19.103313840155945
1968	19.103313840155945
1969	19.103313840155945
1970	19.103313840155945
1971	19.68810916179337
1972	19.68810916179337
1973	21.44249512670565
1974	21.637426900584796
1975	20.66276803118908
1976	20.66276803118908
1977	20.66276803118908
1978	20.66276803118908
1979	20.66276803118908
1980	19.68810916179337
1981	18.51851851851852
1982	17.15399610136452
1983	14.42495126705653
1984	14.42495126705653
1985	13.840155945419102
1986	13.840155945419102
1987	13.840155945419102
1988	14.035087719298245
1989	14.035087719298245
1990	15.009746588693956
1991	15.789473684210526
1992	15.789473684210526
1993	15.789473684210526
1994	15.789473684210526
1995	14.814814814814813
1996	14.814814814814813
1997	13.840155945419102
1998	12.865497076023392
1999	13.060428849902534
2000	13.060428849902534
2001	11.695906432748536
2002	11.695906432748536
2003	11.695906432748536
2004	10.721247563352826
2005	10.526315789473683
2006	10.526315789473683
2007	10.526315789473683
2008	10.526315789473683
2009	10.526315789473683
2010	10.526315789473683
2011	10.526315789473683
2012	10.526315789473683
2013	10.526315789473683
2014	10.526315789473683
2015	10.526315789473683
2016	10.526315789473683
2017	10.526315789473683
2018	10.526315789473683
2019	10.526315789473683
2020	10.526315789473683
2021	10.526315789473683