Year	% of land area
1961	79
1962	78.525
1963	77.2
1964	76.7
1965	75.825
1966	75.675
1967	75.575
1968	75.425
1969	74.775
1970	74.375
1971	73.775
1972	73.9
1973	74.65
1974	73.3
1975	73.425
1976	73.32499999999999
1977	73.175
1978	73.02499999999999
1979	73
1980	72.625
1981	72.425
1982	72.175
1983	71.15
1984	71.375
1985	70.85000000000001
1986	70.475
1987	69.95
1988	69.675
1989	69.35
1990	69.69999999999999
1991	69.25
1992	68.89999999999999
1993	68.475
1994	67.27499999999999
1995	68.15
1996	67.9
1997	67.2
1998	66.8
1999	66.10000000000001
2000	66.175
2001	66.9
2002	66.625
2003	66.45
2004	66.14999999999999
2005	67.675
2006	67.75
2007	66.57499999999999
2008	66.7
2009	65.85
2010	65.64999999999999
2011	67.25
2012	65.60000000000001
2013	65.7
2014	66.315775
2015	65.847475
2016	65.62750000000001
2017	65.7825
2018	65.8125
2019	65.649125
2020	65.499675
2021	65.45