Year	% of land area
1961	20.1202643071084
1962	20.246015959027826
1963	20.371767610947252
1964	20.26887989574045
1965	20.394631547659873
1966	20.406063516016186
1967	20.531815167935616
1968	20.543247136291924
1969	20.554679104648237
1970	20.561538285662024
1971	20.5752566476896
1972	20.94336602876283
1973	20.966229965475456
1974	21.21773326931431
1975	21.22916523767062
1976	21.22916523767062
1977	21.22916523767062
1978	21.466950179481902
1979	21.58126986304502
1980	21.58126986304502
1981	21.58126986304502
1982	21.606420193428903
1983	21.606420193428903
1984	21.606420193428903
1985	21.64071609849784
1986	21.675012003566774
1987	21.675012003566774
1988	21.78933168712989
1989	21.103413585751195
1990	21.103413585751195
1991	22.017971054256122
1992	21.835059560555138
1993	22.566705535359077
1994	21.377780826302672
1995	20.806182408487093
1996	20.806182408487093
1997	19.800169193131673
1998	19.77730525641905
1999	19.434346205729703
2000	19.434346205729703
2001	19.411482269017082
2002	19.86876100326954
2003	19.86876100326954
2004	19.86876100326954
2005	20.21172005395889
2006	20.554679104648237
2007	20.897638155337585
2008	18.725564167638385
2009	18.074230981764597
2010	18.926137410204458
2011	19.685945846380548
2012	19.72854116780254
2013	20.417365385324143
2014	21.350845833486897
2015	21.350845833486897
2016	21.442984557549845
2017	21.489053919581323
2018	21.535123281612798
2019	21.581192643644272
2020	21.74243541075443
2021	21.707883389230826