Year	% of land area
1961	50.363395196386875
1962	49.85365532815189
1963	49.28398905246849
1964	48.707380083239244
1965	48.153060814341416
1966	47.849043918017756
1967	47.39411478830266
1968	47.2231052841206
1969	46.546009960938214
1970	46.54637536586168
1971	46.54637536586168
1972	46.54637536586168
1973	46.54637536586168
1974	46.54637536586168
1975	46.54637536586168
1976	46.54637536586168
1977	46.54637536586168
1978	46.54637536586168
1979	46.54637536586168
1980	46.54637536586168
1981	46.54637536586168
1982	46.54674077078514
1983	46.54710617570861
1984	46.54674077078514
1985	46.54674077078514
1986	46.54674077078514
1987	46.54674077078514
1988	46.545279151091286
1989	46.57816559420321
1990	46.61287906193248
1991	46.64759252966174
1992	46.68230599739101
1993	46.71701946512027
1994	46.752829147619934
1995	46.78827342519613
1996	46.82371770277233
1997	46.85770036065466
1998	46.89241382838392
1999	46.92237703210813
2000	46.95818671460779
2001	46.993265587260524
2002	47.03126769930098
2003	47.174981455700134
2004	47.318695212099286
2005	47.473736521125886
2006	47.55339479444146
2007	47.49109325499052
2008	46.423562771084775
2009	45.430209486642624
2010	46.13891233570481
2011	45.7919603608739
2012	45.58130442249579
2013	44.9219312381015
2014	44.28302072942131
2015	44.118771216323374
2016	43.479495302719705
2017	42.98638135850242
2018	42.37153630846022
2019	42.59077926253978
2020	43.02926517069891
2021	43.1023461553921