Year	% of land area
1961	29.74780701754386
1962	29.7843567251462
1963	29.82090643274854
1964	29.85745614035088
1965	29.894005847953213
1966	29.93421052631579
1967	29.97076023391813
1968	30.007309941520464
1969	30.051169590643273
1970	30.102339181286546
1971	30.043859649122805
1972	30.34356725146199
1973	30.603070175438596
1974	30.89546783625731
1975	31.198830409356727
1976	31.377923976608184
1977	31.56067251461988
1978	31.743421052631575
1979	31.926169590643276
1980	32.10891812865497
1981	32.29166666666667
1982	32.474415204678365
1983	32.65716374269006
1984	32.83991228070175
1985	33.02266081871345
1986	33.20540935672515
1987	33.40643274853801
1988	34.95614035087719
1989	35.08771929824561
1990	34.99634502923977
1991	34.904970760233915
1992	34.81359649122807
1993	34.72222222222222
1994	34.470029239766085
1995	34.53947368421053
1996	34.904970760233915
1997	36.001461988304094
1998	36.44005847953216
1999	36.79093567251462
2000	37.14546783625731
2001	37.510964912280706
2002	37.869152046783626
2003	38.223684210526315
2004	38.63669590643275
2005	39.046052631578945
2006	39.437134502923975
2007	39.8062865497076
2008	40.20285087719298
2009	40.614035087719294
2010	41.08918128654971
2011	41.7141812865497
2012	42.174707602339176
2013	42.85453216374269
2014	43.31140350877193
2015	43.808479532163744
2016	44.23245614035088
2017	44.65277777777778
2018	45.369152046783626
2019	45.75657894736842
2020	46.10380116959064
2021	46.56432748538012