Year	% of land area
1961	15.766423357664234
1962	15.912408759124089
1963	16.05839416058394
1964	16.16788321167883
1965	16.78832116788321
1966	17.335766423357665
1967	17.810218978102192
1968	18.248175182481752
1969	18.613138686131386
1970	19.014598540145986
1971	19.34306569343066
1972	19.708029197080293
1973	20
1974	20.32846715328467
1975	20.547445255474454
1976	20.985401459854014
1977	21.16788321167883
1978	21.27737226277372
1979	21.27737226277372
1980	21.350364963503647
1981	21.45985401459854
1982	21.496350364963504
1983	21.496350364963504
1984	21.496350364963504
1985	21.496350364963504
1986	21.496350364963504
1987	21.532846715328464
1988	21.532846715328464
1989	21.24087591240876
1990	21.13138686131387
1991	21.094890510948904
1992	21.094890510948904
1993	21.05839416058394
1994	21.05839416058394
1995	21.05839416058394
1996	21.05839416058394
1997	21.094890510948904
1998	21.05839416058394
1999	21.05839416058394
2000	21.094890510948904
2001	21.094890510948904
2002	21.094890510948904
2003	21.094890510948904
2004	21.094890510948904
2005	19.635036496350363
2006	21.313868613138688
2007	21.094890510948904
2008	22.26277372262774
2009	22.226277372262775
2010	22.846715328467155
2011	22.7007299270073
2012	22.594890510948908
2013	22.521897810218977
2014	22.467153284671532
2015	22.44890510948905
2016	22.638686131386862
2017	22.335766423357665
2018	22.311897810218976
2019	22.26277372262774
2020	21.88321167883212
2021	21.894160583941606